- Email: [email protected]
Testing of the D-Shuttle personal dosemeter
Radiation Measurements xxx (2017) 1e4
Contents lists available at ScienceDirect
Radiation Measurements journal homepage: www.elsevier.com/locate/radmeas
Testing of the D-Shuttle personal dosemeter *, D. Ekendahl, L. Judas Z. Cemusov a National Radiation Protection Institute, Bartoskova 28, 14000 Prague 4, Czech Republic
h i g h l i g h t s D-Shuttle represents a new type of personal dosemeter. It was used for residents in areas affected by the Fukushima Daiichi nuclear plant accident. We tested it in various radiation and temperature conditions. Its response exhibits a strong dose rate dependence. The dosemeter is not suitable for use in conditions of dose rate higher than 1 mSv/h.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 1 September 2016 Received in revised form 7 February 2017 Accepted 14 March 2017 Available online xxx
A new dosimetry system was developed in Japan (Chiyoda Technol Corporation). It has been used for purposes of continuous long-term personal dose monitoring of residents in the area affected by the Fukushima Daiichi nuclear plant accident. The system includes a Si-diode based dosemeter, namely DShuttle, a small pocket reader, a laboratory table reader and PC with a complementary software application. After insertion of the dosemeter into the pocket reader, the reader's display shows the dose accumulated during the last day and the total dose. In this way, the dose can be checked by the resident anytime. A more detailed dose reconstruction in time can be done in laboratory. We tested this system, and probed its possible usability for first responders that would operate in emergency radiological events. Most of the results were in correspondence with producer's specifications and reference values, but there were several discrepancies observed. © 2017 Elsevier Ltd. All rights reserved.
Keywords: Personal dosimetry D-Shuttle
1. Introduction After the Fukushima Daiichi nuclear plant accident, external radiation doses were measured by area monitors in the affected areas. However, there was a need for monitoring of individual doses of evacuees who returned to these former residential areas. For that reason, a simple, reliable, durable, low-priced and user-friendly dosemeter was required. The requirements were met by the new gamma-ray dosemeter D-Shuttle produced by Chiyoda Technol Corporation (Naito et al., 2015). In order to consider potentials of this new dosemeter, we have tested it in various laboratory conditions. The purpose was to find out if it can be used in more demanding conditions, e.g. for measurement of personal doses of non-radiation workers as first responders operating in emergency radiological events. These personnel including firefighters,
* Corresponding author. ). E-mail address: [email protected] (Z. Cemusov a
policemen and emergency medical workers, are not usually equipped with conventional personal dosemeters that can easily identify the level of external exposure. Equipping these personnel with common electronic personal dosemeters would be considerably costly. Therefore, alternatives are sought. 2. Materials and methods 2.1. Dosemeter and its accessories D-Shuttle is a small and very light Si-diode based personal gamma-ray dosemeter (Fig. 1). The dosemeter itself is without a display. Dose can be displayed via a compatible pocket reader. After inserting the dosemeter into the reader, two values of personal dose equivalent at the depth of 10 mm, Hp(10), are shown e the dose accumulated during the last day and the total dose accumulated during the whole period from resetting of the dosemeter. The dose reading can be easily done anytime by the person wearing the dosemeter.
http://dx.doi.org/10.1016/j.radmeas.2017.03.011 1350-4487/© 2017 Elsevier Ltd. All rights reserved.
a, Z., et al., Testing of the D-Shuttle personal dosemeter, Radiation Measurements (2017), http:// Please cite this article in press as: Cemusov dx.doi.org/10.1016/j.radmeas.2017.03.011
et al. / Radiation Measurements xxx (2017) 1e4 Z. Cemusov a
2
Table 1 D-Shuttle characteristics declared by Chiyoda Technol Corporation. Dimensions and weight Energy range response relative to 60Co Angular response Measuring range Operational temperature response relative to 20 C Battery life Memory Data transfer
Fig. 1. D-Shuttle dosemeter with its pocket reader.
To make the Hp(10) measurement representative, it is recommended to wear the dosemeter on the chest (a sachet with a strap is provided by the manufacturer). Wearing the dosemeter hidden in a bag can lead to underestimation of the dose estimate. D-Shuttle characteristics declared by the manufacturer are given in Table 1. As a complement, Chiyoda Technol provides a compatible software (SW) and a table reader connectable via USB cable to PC, which enables dose reconstruction in time and resetting the collected data to zero values. Besides the total and day doses, it also shows dose distribution in a chosen time period. The continuous operation of the system is at least 1 year without the need to change battery. However, the battery exchange cannot be done by a common user but only by the manufacturer.
68 32 14 mm3, 23 g 60 keVe1.25 MeV ±30% ±10% in the range ±60 0.1 mSve99.9999 mSv 20 C e þ40 C at least ±10% 1 year yes reader
(6) dose rate response e the dosemeter was irradiated using a 137 Cs source in conditions with different dose equivalent rates in the range of about 0.02e200 mSv/h, (7) ambient temperature influence e dosemeters were placed inside a special box enabling to keep the temperature at the values close to the limits of the operational range, i.e. 15 C and 35 C, they were irradiated through a plastic window using a 137Cs source, (8) high dose response e using a 60Co source, the dosemeter was irradiated to air kerma value of 3 Gy at dose rate of 0.9 Gy/h. The stated values are related to the reference point of irradiation in the centre of the dosemeter. All these experiments were performed with each single dosemeter fixed to the ICRU slab phantom. The only exception makes rotational geometry, as a part of angular response test, whose measurement was realized on the chest of an anthropomorphic Rando phantom. The dosemeter was centered at 15 cm below the thyroid and 4 cm left of the midline.
3. Results and discussion
2.2. Test parameters To examine the properties of the instrument, the following dosimetric characteristics related to Hp(10) measurements were tested: (1) homogeneity of response - 5 dosemeters were irradiated under the same conditions using a source of 137Cs, their results were evaluated by calculation of standard deviation, (2) reproducibility of response e one dosemeter was irradiated 5 times under the same conditions using a source of 137Cs, results obtained for the 5 repeated exposures were evaluated by calculation of standard deviation, (3) dose response e the dosemeters were irradiated using a 137 Cs source in conditions of constant dose rate of 9.46 mSv/h to different doses in the range of 0.12 mSve121 mSv, (4) energy response e the dosemeters were irradiated using different radiation qualities N-80, N-150, N-250, S-Cs and SCo (ISO 4037-1, 1996) in conditions of constant air kerma rate of 2 mGy/h, Hp(10)m results measured were compared with Hp(10)t reference (true) values (ISO 4037-3, 1999), (5) angular response e using a 137Cs source, the dosemeters were irradiated for angles of radiation incidence of 0 e ±60 at constant air kerma rate of 2 mGy/h, Hp(10)m results measured were compared with Hp(10)t reference (true) values (ISO 4037-3, 1999), in addition, rotational geometry was assessed as an average response for the range 0 e360 with 30 spacing, performed under the same conditions,
Tables 2e5 contain results of the laboratory measurements (3)e(6) executed in the way described in section 2.2. All outcomes are discussed below. (1) Homogeneity of the response that we obtained was 0.8%. (2) Reproducibility of the response was assessed as 1.1%. (3) The result of dose response test is shown in Fig. 2. The measurement of dose response was performed previous to the dose rate response test. Results of dose rate response (see part (6) and Table 5) obtained later explain the detected dose underestimation given in Table 2. For purposes of dose response test, in which linear behavior of dose response was checked in the given dose range (see Fig. 2), the observed dose underestimation was considered insignificant, and the test was not repeated with a lower dose rate applied. To obtain the true value with acceptable uncertainty, the lowest dose measured during this test was set to 0.12 mSv. Nevertheless, the dosemeters were exposed to the natural background radiation around 0.1 mSv/h and their sensitivity was sufficiently high, in agreement with the manufacturer's project. (4) Energy response test results are summarized in Table 3. The dose rates applied during the energy response tests were adapted to the dose rate response of the dosemeter (6). Despite this fact, a considerable Hp(10) underestimation by a factor of 0.6 was detected for radiation qualities of N-150 and N-250. The response to other tested energies fitted the reference values and manufacturer's data.
, Z., et al., Testing of the D-Shuttle personal dosemeter, Radiation Measurements (2017), http:// Please cite this article in press as: Cemusov a dx.doi.org/10.1016/j.radmeas.2017.03.011
et al. / Radiation Measurements xxx (2017) 1e4 Z. Cemusov a
3
Table 4 D-Shuttle results of the test (5)- angular response. The measured Hp(10)m values were compared with true Hp(10)t values for the radiation quality S-Cs and the particular angle of incidence (ISO 4037-3, 1999, Zankl, 1999). Angle of incidence
Hp(10)m/Hp(10)t
0 ±30 ±60 ROT
1.08 1.04; 1.08 1.04; 1.09 1.10
Table 5 D-Shuttle results of the test (6)- dose rate response. Fig. 2. Dose response linearity test (3). The measured Hp(10)m depending on the applied air kerma value.
Table 2 D-Shuttle results of the test (3)- dose response. True value [mSv]
Measured value [mSv]
Hp(10)m/Hp(10)t
0.121 1.21 12.1 99.2 121
0.111 1.063 10.549 87.970 106.037
0.917 0.879 0.872 0.887 0.876
Table 3 D-Shuttle results of the test (4)- energy response. The values measured for the particular radiation qualities were compared with appropriate true values (ISO 4037-3, 1999). Radiation quality
Hp(10)m/Hp(10)t
N-80 N-150 N-250 S-Cs S-Co
0.98 0.62 0.60 1.06 0.94
(5) Angular response for the angles 0 e ±60 is in correspondence with reference (see Table 4) and manufacturer's values. The measured response of 1.145 mSv for rotational geometry is slightly higher than the reference value of 1.045 mSv, calculated by means of conversion coefficients given in Zankl (1999). (6) A problem was revealed during the dose rate response test. It was found that D-Shuttle dosemeter measures correctly at rates less than 1 mSv/h. While increasing the dose rate, the dosemeter tended to underestimate Hp(10), and it ceased to be usable at rates of tens mSv/h, when a significant dose underestimation by a factor <0.5 was observed. It means that the system works well only in a stable low dose-rate environment. The details are in Table 5. (7) During the testing at different temperatures the dosemeters worked correctly except one of three tested units that indicated an absurdly high value at 15 C. It overestimated the applied dose value by a factor of 10, afterwards, the dosemeter worked correctly again. Otherwise, our results confirmed the trend of a slight overestimation at low temperatures and underestimation at high temperatures, within ±10% in the operational temperature range. (8) The purpose of the irradiation to the dose value out of the declared measuring range was to check the behavior of the dosemeter exposed to a high dose. The exposure did not destroy the dosemeter and no influence on the subsequent
True value [mSv/h]
Measured value [mSv/h]
Ḣp(10)m/Ḣp(10)t
0.024 0.274 2.839 34.11 193.55
0.028 0.309 2.741 17.992 33.662
1.168 1.127 0.965 0.527 0.174
functioning was observed, but the right value could not be displayed. An error message “over” appeared on the display of the pocket reader. With help of the table reader, the dose value underestimated by a factor <0.01 was read. The result was affected by the applied high dose rate. A disadvantage of the system may be that the pocket reader indicates the dose accumulated during the last day, not last 24 h, i.e. the current dose is not displayed. This fact makes the dosemeter unsuitable for emergency responders, who would operate in unpredictable and unstable dose rate conditions. The only way to get the current dose is to use the table reader with PC, or to record the total dose, which is also displayed and whose value is updated continuously. The table reader together with the proper SW application enable to perform dose reconstruction in time up to a year back to the past (until the reset of the dosemeter was performed). However, it was revealed that this dose reconstruction is not always reliable. The dose accumulated in a single irradiation taking a few minutes was divided into several hours. Time shifts of the dose peaks occurred too. What is more, wrong indications were noticed, e.g. the computed month dose was lower than a dose registered in one day in this month, and strange dose peaks in a stable laboratory environment appeared. So to pay attention during handling the data is recommended. 4. Conclusion The results show that the D-Shuttle system is suitable for stable low-dose rate radiation conditions. Then it may serve as a useful tool to reassure the people about the safe radiation situation. However, the time reconstruction of the dose is not always reliable. Acknowledgements This work was accomplished in conjunction with the research project “Methodologies for determination of personal radiation doses in the view of nuclear and radiological terrorism threats”, identification code VI20152020033, funded by the Ministry of the Interior of the Czech Republic. References International Organization for Standardization, 1996. X and Gamma Reference
a, Z., et al., Testing of the D-Shuttle personal dosemeter, Radiation Measurements (2017), http:// Please cite this article in press as: Cemusov dx.doi.org/10.1016/j.radmeas.2017.03.011
4
et al. / Radiation Measurements xxx (2017) 1e4 Z. Cemusov a
Radiation for Calibrating Dosemeters and Doserate Meters and for Determining Their Response as a Function of Photon Energy- Part 1: Radiation Characteristics and Production Methods. ISO 4037e1. International Organization for Standardization, 1999. X and Gamma Reference Radiation for Calibrating Dosemeters and Doserate Meters and for Determining Their Response as a Function of Photon Energy- Part 3: Calibration of Area and Personal Dosemeters and the Measurement of Their Response as a Function of
Energy and Angle of Incidence. ISO 4037e3. Naito, W., Uesaka, M., Yamada, C., Ishii, H., 2015. Evaluation of dose from external irradiation for individuals living in areas affected by the Fukushima Daiichi nuclear plant accident. Radiat. Prot. Dosim. 163, 353e361. Zankl, M., 1999. Personal dose equivalent for photons and its variation with dosemeter position. Health Phys. 76, 162e170.
, Z., et al., Testing of the D-Shuttle personal dosemeter, Radiation Measurements (2017), http:// Please cite this article in press as: Cemusov a dx.doi.org/10.1016/j.radmeas.2017.03.011
Contents lists available at ScienceDirect
Radiation Measurements journal homepage: www.elsevier.com/locate/radmeas
Testing of the D-Shuttle personal dosemeter *, D. Ekendahl, L. Judas Z. Cemusov a National Radiation Protection Institute, Bartoskova 28, 14000 Prague 4, Czech Republic
h i g h l i g h t s D-Shuttle represents a new type of personal dosemeter. It was used for residents in areas affected by the Fukushima Daiichi nuclear plant accident. We tested it in various radiation and temperature conditions. Its response exhibits a strong dose rate dependence. The dosemeter is not suitable for use in conditions of dose rate higher than 1 mSv/h.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 1 September 2016 Received in revised form 7 February 2017 Accepted 14 March 2017 Available online xxx
A new dosimetry system was developed in Japan (Chiyoda Technol Corporation). It has been used for purposes of continuous long-term personal dose monitoring of residents in the area affected by the Fukushima Daiichi nuclear plant accident. The system includes a Si-diode based dosemeter, namely DShuttle, a small pocket reader, a laboratory table reader and PC with a complementary software application. After insertion of the dosemeter into the pocket reader, the reader's display shows the dose accumulated during the last day and the total dose. In this way, the dose can be checked by the resident anytime. A more detailed dose reconstruction in time can be done in laboratory. We tested this system, and probed its possible usability for first responders that would operate in emergency radiological events. Most of the results were in correspondence with producer's specifications and reference values, but there were several discrepancies observed. © 2017 Elsevier Ltd. All rights reserved.
Keywords: Personal dosimetry D-Shuttle
1. Introduction After the Fukushima Daiichi nuclear plant accident, external radiation doses were measured by area monitors in the affected areas. However, there was a need for monitoring of individual doses of evacuees who returned to these former residential areas. For that reason, a simple, reliable, durable, low-priced and user-friendly dosemeter was required. The requirements were met by the new gamma-ray dosemeter D-Shuttle produced by Chiyoda Technol Corporation (Naito et al., 2015). In order to consider potentials of this new dosemeter, we have tested it in various laboratory conditions. The purpose was to find out if it can be used in more demanding conditions, e.g. for measurement of personal doses of non-radiation workers as first responders operating in emergency radiological events. These personnel including firefighters,
* Corresponding author. ). E-mail address: [email protected] (Z. Cemusov a
policemen and emergency medical workers, are not usually equipped with conventional personal dosemeters that can easily identify the level of external exposure. Equipping these personnel with common electronic personal dosemeters would be considerably costly. Therefore, alternatives are sought. 2. Materials and methods 2.1. Dosemeter and its accessories D-Shuttle is a small and very light Si-diode based personal gamma-ray dosemeter (Fig. 1). The dosemeter itself is without a display. Dose can be displayed via a compatible pocket reader. After inserting the dosemeter into the reader, two values of personal dose equivalent at the depth of 10 mm, Hp(10), are shown e the dose accumulated during the last day and the total dose accumulated during the whole period from resetting of the dosemeter. The dose reading can be easily done anytime by the person wearing the dosemeter.
http://dx.doi.org/10.1016/j.radmeas.2017.03.011 1350-4487/© 2017 Elsevier Ltd. All rights reserved.
a, Z., et al., Testing of the D-Shuttle personal dosemeter, Radiation Measurements (2017), http:// Please cite this article in press as: Cemusov dx.doi.org/10.1016/j.radmeas.2017.03.011
et al. / Radiation Measurements xxx (2017) 1e4 Z. Cemusov a
2
Table 1 D-Shuttle characteristics declared by Chiyoda Technol Corporation. Dimensions and weight Energy range response relative to 60Co Angular response Measuring range Operational temperature response relative to 20 C Battery life Memory Data transfer
Fig. 1. D-Shuttle dosemeter with its pocket reader.
To make the Hp(10) measurement representative, it is recommended to wear the dosemeter on the chest (a sachet with a strap is provided by the manufacturer). Wearing the dosemeter hidden in a bag can lead to underestimation of the dose estimate. D-Shuttle characteristics declared by the manufacturer are given in Table 1. As a complement, Chiyoda Technol provides a compatible software (SW) and a table reader connectable via USB cable to PC, which enables dose reconstruction in time and resetting the collected data to zero values. Besides the total and day doses, it also shows dose distribution in a chosen time period. The continuous operation of the system is at least 1 year without the need to change battery. However, the battery exchange cannot be done by a common user but only by the manufacturer.
68 32 14 mm3, 23 g 60 keVe1.25 MeV ±30% ±10% in the range ±60 0.1 mSve99.9999 mSv 20 C e þ40 C at least ±10% 1 year yes reader
(6) dose rate response e the dosemeter was irradiated using a 137 Cs source in conditions with different dose equivalent rates in the range of about 0.02e200 mSv/h, (7) ambient temperature influence e dosemeters were placed inside a special box enabling to keep the temperature at the values close to the limits of the operational range, i.e. 15 C and 35 C, they were irradiated through a plastic window using a 137Cs source, (8) high dose response e using a 60Co source, the dosemeter was irradiated to air kerma value of 3 Gy at dose rate of 0.9 Gy/h. The stated values are related to the reference point of irradiation in the centre of the dosemeter. All these experiments were performed with each single dosemeter fixed to the ICRU slab phantom. The only exception makes rotational geometry, as a part of angular response test, whose measurement was realized on the chest of an anthropomorphic Rando phantom. The dosemeter was centered at 15 cm below the thyroid and 4 cm left of the midline.
3. Results and discussion
2.2. Test parameters To examine the properties of the instrument, the following dosimetric characteristics related to Hp(10) measurements were tested: (1) homogeneity of response - 5 dosemeters were irradiated under the same conditions using a source of 137Cs, their results were evaluated by calculation of standard deviation, (2) reproducibility of response e one dosemeter was irradiated 5 times under the same conditions using a source of 137Cs, results obtained for the 5 repeated exposures were evaluated by calculation of standard deviation, (3) dose response e the dosemeters were irradiated using a 137 Cs source in conditions of constant dose rate of 9.46 mSv/h to different doses in the range of 0.12 mSve121 mSv, (4) energy response e the dosemeters were irradiated using different radiation qualities N-80, N-150, N-250, S-Cs and SCo (ISO 4037-1, 1996) in conditions of constant air kerma rate of 2 mGy/h, Hp(10)m results measured were compared with Hp(10)t reference (true) values (ISO 4037-3, 1999), (5) angular response e using a 137Cs source, the dosemeters were irradiated for angles of radiation incidence of 0 e ±60 at constant air kerma rate of 2 mGy/h, Hp(10)m results measured were compared with Hp(10)t reference (true) values (ISO 4037-3, 1999), in addition, rotational geometry was assessed as an average response for the range 0 e360 with 30 spacing, performed under the same conditions,
Tables 2e5 contain results of the laboratory measurements (3)e(6) executed in the way described in section 2.2. All outcomes are discussed below. (1) Homogeneity of the response that we obtained was 0.8%. (2) Reproducibility of the response was assessed as 1.1%. (3) The result of dose response test is shown in Fig. 2. The measurement of dose response was performed previous to the dose rate response test. Results of dose rate response (see part (6) and Table 5) obtained later explain the detected dose underestimation given in Table 2. For purposes of dose response test, in which linear behavior of dose response was checked in the given dose range (see Fig. 2), the observed dose underestimation was considered insignificant, and the test was not repeated with a lower dose rate applied. To obtain the true value with acceptable uncertainty, the lowest dose measured during this test was set to 0.12 mSv. Nevertheless, the dosemeters were exposed to the natural background radiation around 0.1 mSv/h and their sensitivity was sufficiently high, in agreement with the manufacturer's project. (4) Energy response test results are summarized in Table 3. The dose rates applied during the energy response tests were adapted to the dose rate response of the dosemeter (6). Despite this fact, a considerable Hp(10) underestimation by a factor of 0.6 was detected for radiation qualities of N-150 and N-250. The response to other tested energies fitted the reference values and manufacturer's data.
, Z., et al., Testing of the D-Shuttle personal dosemeter, Radiation Measurements (2017), http:// Please cite this article in press as: Cemusov a dx.doi.org/10.1016/j.radmeas.2017.03.011
et al. / Radiation Measurements xxx (2017) 1e4 Z. Cemusov a
3
Table 4 D-Shuttle results of the test (5)- angular response. The measured Hp(10)m values were compared with true Hp(10)t values for the radiation quality S-Cs and the particular angle of incidence (ISO 4037-3, 1999, Zankl, 1999). Angle of incidence
Hp(10)m/Hp(10)t
0 ±30 ±60 ROT
1.08 1.04; 1.08 1.04; 1.09 1.10
Table 5 D-Shuttle results of the test (6)- dose rate response. Fig. 2. Dose response linearity test (3). The measured Hp(10)m depending on the applied air kerma value.
Table 2 D-Shuttle results of the test (3)- dose response. True value [mSv]
Measured value [mSv]
Hp(10)m/Hp(10)t
0.121 1.21 12.1 99.2 121
0.111 1.063 10.549 87.970 106.037
0.917 0.879 0.872 0.887 0.876
Table 3 D-Shuttle results of the test (4)- energy response. The values measured for the particular radiation qualities were compared with appropriate true values (ISO 4037-3, 1999). Radiation quality
Hp(10)m/Hp(10)t
N-80 N-150 N-250 S-Cs S-Co
0.98 0.62 0.60 1.06 0.94
(5) Angular response for the angles 0 e ±60 is in correspondence with reference (see Table 4) and manufacturer's values. The measured response of 1.145 mSv for rotational geometry is slightly higher than the reference value of 1.045 mSv, calculated by means of conversion coefficients given in Zankl (1999). (6) A problem was revealed during the dose rate response test. It was found that D-Shuttle dosemeter measures correctly at rates less than 1 mSv/h. While increasing the dose rate, the dosemeter tended to underestimate Hp(10), and it ceased to be usable at rates of tens mSv/h, when a significant dose underestimation by a factor <0.5 was observed. It means that the system works well only in a stable low dose-rate environment. The details are in Table 5. (7) During the testing at different temperatures the dosemeters worked correctly except one of three tested units that indicated an absurdly high value at 15 C. It overestimated the applied dose value by a factor of 10, afterwards, the dosemeter worked correctly again. Otherwise, our results confirmed the trend of a slight overestimation at low temperatures and underestimation at high temperatures, within ±10% in the operational temperature range. (8) The purpose of the irradiation to the dose value out of the declared measuring range was to check the behavior of the dosemeter exposed to a high dose. The exposure did not destroy the dosemeter and no influence on the subsequent
True value [mSv/h]
Measured value [mSv/h]
Ḣp(10)m/Ḣp(10)t
0.024 0.274 2.839 34.11 193.55
0.028 0.309 2.741 17.992 33.662
1.168 1.127 0.965 0.527 0.174
functioning was observed, but the right value could not be displayed. An error message “over” appeared on the display of the pocket reader. With help of the table reader, the dose value underestimated by a factor <0.01 was read. The result was affected by the applied high dose rate. A disadvantage of the system may be that the pocket reader indicates the dose accumulated during the last day, not last 24 h, i.e. the current dose is not displayed. This fact makes the dosemeter unsuitable for emergency responders, who would operate in unpredictable and unstable dose rate conditions. The only way to get the current dose is to use the table reader with PC, or to record the total dose, which is also displayed and whose value is updated continuously. The table reader together with the proper SW application enable to perform dose reconstruction in time up to a year back to the past (until the reset of the dosemeter was performed). However, it was revealed that this dose reconstruction is not always reliable. The dose accumulated in a single irradiation taking a few minutes was divided into several hours. Time shifts of the dose peaks occurred too. What is more, wrong indications were noticed, e.g. the computed month dose was lower than a dose registered in one day in this month, and strange dose peaks in a stable laboratory environment appeared. So to pay attention during handling the data is recommended. 4. Conclusion The results show that the D-Shuttle system is suitable for stable low-dose rate radiation conditions. Then it may serve as a useful tool to reassure the people about the safe radiation situation. However, the time reconstruction of the dose is not always reliable. Acknowledgements This work was accomplished in conjunction with the research project “Methodologies for determination of personal radiation doses in the view of nuclear and radiological terrorism threats”, identification code VI20152020033, funded by the Ministry of the Interior of the Czech Republic. References International Organization for Standardization, 1996. X and Gamma Reference
a, Z., et al., Testing of the D-Shuttle personal dosemeter, Radiation Measurements (2017), http:// Please cite this article in press as: Cemusov dx.doi.org/10.1016/j.radmeas.2017.03.011
4
et al. / Radiation Measurements xxx (2017) 1e4 Z. Cemusov a
Radiation for Calibrating Dosemeters and Doserate Meters and for Determining Their Response as a Function of Photon Energy- Part 1: Radiation Characteristics and Production Methods. ISO 4037e1. International Organization for Standardization, 1999. X and Gamma Reference Radiation for Calibrating Dosemeters and Doserate Meters and for Determining Their Response as a Function of Photon Energy- Part 3: Calibration of Area and Personal Dosemeters and the Measurement of Their Response as a Function of
Energy and Angle of Incidence. ISO 4037e3. Naito, W., Uesaka, M., Yamada, C., Ishii, H., 2015. Evaluation of dose from external irradiation for individuals living in areas affected by the Fukushima Daiichi nuclear plant accident. Radiat. Prot. Dosim. 163, 353e361. Zankl, M., 1999. Personal dose equivalent for photons and its variation with dosemeter position. Health Phys. 76, 162e170.
, Z., et al., Testing of the D-Shuttle personal dosemeter, Radiation Measurements (2017), http:// Please cite this article in press as: Cemusov a dx.doi.org/10.1016/j.radmeas.2017.03.011