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Journal List > Prog Med Phys > v.27(3) > 1098546

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Lee, Kim, Kwon, Kim, Kim, Park, Park, and Jung: Analysis of Trends in Dose through Evaluation of Spatial Dose Rate and Surface Contamination in Radiation-Controlled Area and Personal Exposed Dose of Radiation Worker at the Korea Institute of Radiological and Medical Sciences (KIRAMS)
Original Article

Prog Med Phys 2016;27(3):146-155.

Published online: 30 September 2016

DOI: https://doi.org/10.14316/pmp.2016.27.3.146

Analysis of Trends in Dose through Evaluation of Spatial Dose Rate and Surface Contamination in Radiation-Controlled Area and Personal Exposed Dose of Radiation Worker at the Korea Institute of Radiological and Medical Sciences (KIRAMS)

Bu Hyung Lee*, †, Sung Ho Kim*, †, Soo Il Kwon*, Jae Seok Kim*, Gi-sub Kim†, Min Seok Park†, Seungwoo Park†, Haijo Jung†

*Department of Medical Physics, Kyonggi University, Suwon, Korea

†Korea Institute of Radiological and Medical Sciences, Seoul, Korea

Correspondence: Haijo Jung (haijo@kirams.re.kr) Tel: 82-2-970-1346, Fax: 82-2-970-1963

Received 12 September 2016       Revised 23 September 2016       Accepted 24 September 2016

Copyright © 2016 Korean Society of Medical Physics

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

As the probability of exposure to radiation increases due to an increase in the use of radioisotopes and radiation generators, the importance of a radiation safety management field is being highlighted. We intend to help radiation workers with exposure management by identifying the degree of radiation exposure and contamination to determine an efficient method of radiation safety management. The personal exposure doses of the radiation workers at the Korea Institute of Radiological & Medical Sciences measured every quarter during a five-year period from Jan. 1, 2011 till Dec. 31, 2015 were analyzed using a TLD (thermoluminescence dosimeter). The spatial dose rates of radiation-controlled areas were measured using a portable radioscope, and the level of surface contamination was measured at weekly intervals using a piece of smear paper and a low background alpha/beta counter. Though the averages of the depth doses and the surface doses in 2012 increased from those in 2011 by about 14%, the averages were shown to have decreased every year after that. The exposure dose of 27 mSv in 2012 increased from that in 2011 in radiopharmaceutical laboratories and, in the case of the spatial dose rate, the rate of decrease in 2012 was shown to be similar to the annual trend of the whole institute. In the case of the surface contamination level, as the remaining radiation-controlled area with the exception of the I-131 treatment ward showed a low value less than 1.0 kBq/m², the annual trend of the I-131 treatment ward was shown to be similar to that of the entire institute. In conclusion, continuous attention should be paid to dose monitoring of the radiation-controlled areas where unsealed sources are handled and the workers therein.

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Keywords: Radiation-controlled area, Radiation worker, Personal exposure dose, Spatial dose rate and Surface contamination

pmp-27-146f1.tif
Fig. 1.
Annual collective dose of radiation workers by position between 2011 and 2015.

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pmp-27-146f2.tif
Fig. 2.
Annual average of the spatial dose rate by position between 2011 and 2015.

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pmp-27-146f3.tif
Fig. 3.
Annual average of the surface contamination by position between 2011 and 2015.

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Table 1.
Annual average effective dose distribution by position between 2011 and 2015.
Position mSv
2011 2012 2013 2014 2015
Neutron therapy facility (P1) 0.27 1.9 1.9 1.4 1.4
Radioactive pharmaceuticals research team (P2) 2.0 3.5 2.9 2.3 2.9
Radioactive pharmaceuticals production team (P3) 2.6 2.4 2.5 2.6 2.4
Nuclear medicine (P4) 1.2 1.1 1.1 1.0 1.1
I-131 treatment ward (P5) 1.0 1.1 1.1 0.90 0.90
Avg. 1.4 2.0 1.9 1.6 1.7

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Table 2.
Number of workers exceeding the mean effective dose in their position between 2011 and 2015.
Position 2011
 2012
 2013
 2014
 2015
N* % N* % N* % N* % N* %
Neutron therapy facility (P1) 1 3.70 2 6.90 1 3.85 1 4.35 1 6.67
Radioactive pharmaceuticals research team (P2) 4 14.81 3 10.34 2 7.69 3 13.04 2 13.33
Radioactive pharmaceuticals production center (P3) 8 29.63 9 31.03 7 26.92 7 30.43 5 33.33
Nuclear medicine (P4) 10 37.04 10 34.48 10 38.46 10 43.48 6 40.0
I-131 treatment ward (P5) 4 14.81 5 17.24 6 23.08 2 8.70 1 6.67
Total 27 100.00 29 100.00 26 100.00 23 100.00 15 100.00

* The number of workers exceeding the mean effective dose in their positions.

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Table 3.
Mean and standard deviation of the depth dose and surface dose between 2011 and 2015.
Year N* Mean±S.D.†
Deep dose Shallow dose
2011 292 0.70±1.7a 0.78±2.1a
2012 335 0.80±1.9a 0.89±2.3a
2013 372 0.63±1.6a,b 0.72±2.3a,b
2014 386 0.62±1.7a,b 0.64±1.6a,b
2015 446 0.42±1.3c 0.45±1.5c
Total 1,831 0.62±1.6 0.68±2.0

Unit: mSv.

a,b,c The same parameters show no difference between years.

* Number of measurements according to year.

† Harmonic mean±harmonic standard deviation.

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Table 4.
Mean and standard deviation of the depth dose and surface dose by age between 2011 and 2015.
Deep dose
 unit : mSv
Year
 2011
 2012
 2013
 2014
 2015
Age N* mean±S.D.† N* mean±S.D.† N* mean±S.D.† N* mean±S.D.† N* mean±S.D.†
20 61 0.61±1.5 74 0.69±1.2 85 0.63±1.5 90 0.48±1.4 109 0.23±0.57
30 114 0.73±1.8 136 0.65±1.1 143 0.56±0.91 150 0.55±1.3 179 0.36±1.0
40 80 0.79±1.9 75 1.2±3.2 81 0.77±2.4 80 0.78±2.2 90 0.49±1.6
50 34 0.65±1.8 46 0.84±1.7 54 0.68±2.0 58 0.85±2.1 60 0.77±2.1
60 3 0.05±0.06 4 0.11±0.11 9 0.18±0.15 8 0.19±0.2 8 1.0±2.0
Total 292 0.70±1.7 335 0.80±1.9 372 0.63±1.6 386 0.62±1.7 446 0.42±1.3
Shallow dose
 unit : mSv
Year
 2011
 2012
 2013
 2014
 2015
Age N mean±S.D.† N mean±S.D.† N mean±S.D.† N mean±S.D.† N mean±S.D.†
20 61 0.61±1.5 74 0.73±1.2 85 0.67±1.5 90 0.50±1.4 109 0.24±0.56
30 114 0.83±2.0 136 0.82±2.4 143 0.65±1.5 150 0.60±1.3 179 0.37±0.96
40 80 0.90±2.5 75 1.2±3.2 81 0.97±3.9 80 0.72±2.1 90 0.59±2.3
50 34 0.72±2.1 46 0.84±1.7 54 0.69±2.0 58 0.92±2.1 60 0.77±2.1
60 3 0.05±0.06 4 0.11±0.11 9 0.23±0.29 8 0.22±0.21 8 1.0±2.0
Total 292 0.78±2.0 335 0.89±2.3 372 0.72±2.3 386 0.64±1.6 446 0.45±1.5

* The number of measurement by age.

† Harmonic mean±harmonicstandard deviation.

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Table 5.
Mean and standard deviation of the depth dose and surface dose by gender between 2011 and 2015.
Deep dose
 unit : mSv
Year
 2011
 2012
 2013
 2014
 2015
Gender N* mean±S.D.† N* mean±S.D.† N* mean±S.D.† N* mean±S.D.† N* mean±S.D.†
M 182 0.91±2.0a,x 196 0.98±2.2a,x 214 0.77±1.9a,b,x 216 0.77±1.8a,b,x 248 0.53±1.4b,x
F 110 0.37±1.1a,y 139 0.56±1.2a,y 158 0.44±1.2a,b,y 170 0.43±1.4a,b,y 198 0.29±1.1b,y
Total 292 0.70±1.7 335 0.80±1.9 372 0.63±1.6 386 0.62±1.7 446 0.42±1.3
Shallow dose
 unit : mSv
Year
 2011
 2012
 2013
 2014
 2015
Gender N mean±S.D.† N mean±S.D.† N mean±S.D.† N mean±S.D.† N mean±S.D.†
M 182 1.0±2.3a,x 196 1.1±2.8a,x 214 0.91±2.8a,b,x 216 0.82±1.9a,b,x 248 0.57±1.8b,x
F 110 0.42±1.4a,y 139 0.58±1.2a,y 158 0.45±1.2a,b,y 170 0.42±1.3a,b,y 198 0.29±1.1b,y
Total 292 0.78±2.1 335 0.89±2.3 372 0.72±2.3 386 0.64±1.6 446 0.45±1.5

* Number of measurement by gender.

† Harmonic mean±harmonic standard deviation.

a,b Same parameters show no difference between years.

x,y Same parameters show no difference between gender.

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Table 6.
Mean spatial dose rate and mean distribution by position between 2011 and 2015. Unit: μSv/h
Radiation-controlled area 2011 2012 2013 2014 2015
Position 1 (n=12) N 91 196 378 411 441
Mean distribution 0.53∼2.9 4.5∼23 0.60∼15 0.32∼8.0 0.37∼0.99
Mean±SD† 2.4±3.71a,x 14±55a,x,y 4.3±31a,y,z 1.3±6.8a,y,z 0.66±1.6a,z
Position 2 (n=16) N 150 702 655 704 703
Mean distribution 19∼21 0.18∼0.40 0.20∼0.95 0.20∼0.68 0.18∼0.43
Mean±SD† 20±13b,x 0.24±0.56b,x,y 2.0±5.5b,y,z 0.30±1.6b,y,z 0.26±0.33b,z
Position 3 (n=30) N 891 1319 1257 1380 1289
Mean distribution 0.48∼6.16 1.3∼4.2 1.5∼3.8 1.6∼3.0 0.78∼21
Mean±SD† 1.1±5.5c,x 2.0±5.5c,x,y 2.3±8.0c,y,z 2.3±5.9c,y,z 3.5±28c,z
Position 4 (n=28) N 840 1229 1175 1288 1176
Mean distribution 0.82∼2.5 0.47∼1.5 0.62∼1.4 0.46∼1.2 0.30∼0.67
Mean±SD† 1.3±3.6c,x 1.0±2.8c,x,y 1.0±2.8c,y,z 0.89±2.5c,y,z 0.51±1.2c,z
Position 5 (n=41) N 1228 1761 1553 1804 1517
Mean distribution 0.20∼0.37 0.27∼0.88 0.27∼0.61 0.24∼0.38 0.21∼0.33
Mean±SD† 0.24±0.34d,x 0.43±1.9d,x,y 0.34±0.73d,y,z 0.30±0.30d,y,z 0.25±0.20d,z
Total N 3200 5207 5018 5587 5126
Mean±SD† 1.7±6.2 1.5±11 1.3±9.7 0.99±3.8 1.2±14

* Number of measurements by position.

† Harmonic mean±Harmonic standard deviation.

a,b,c,d The same parameters show no difference between years.

x,y The same parameters show no difference between positions.

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Table 7.
Mean surface contamination and mean distribution by position between 2011 and 2015. Unit: kBq/m2
Radiation-controlled area 2011 2012 2013 2014 2015
Position 2 (n=16) N - 671 638 702 704
Mean distribution - 0∼1.5 0∼0.11 0∼0.18 0∼0.04
Mean±SD† - 0.32±1.4b,x 0.03±0.18c,x 0.03±0.24d,x 0.01±0.05d,x
Position 3 (n=30) N 891 1348 1258 1378 1287
Mean distribution 0.11∼2.1 0.10∼2.4 0.03∼1.8 0.01∼4.5 0.01∼1.2
Mean±SD† 0.76±2.0a,x 0.82±3.3b,x 0.30±1.8c,x 0.55±4.1d,x 0.43±1.9d,x
Position 4 (n=28) N 840 1231 1146 1287 1176
Mean distribution 0.00∼0.47 0.01∼5.3 0.01∼0.15 0.01∼0.72 0.00∼0.35
Mean±SD† 0.07±0.53a,x 0.88±12b,x 0.05±0.33c,x 0.11±1.9d,x 0.05±0.82d,x
Position 5 (n=41) N 1230 1732 1548 1803 1497
Mean distribution 2.31∼20.34 2.71∼15.52 0.98∼12 0.87∼4.1 0.06∼3.8
Mean±SD† 9.3±45a,y 7.1±24b,y 5.4±22c,y 2.5±10d,y 1.2±9.6d,y
Total N 2961 4982 4590 5170 4664
Mean±SD† 4.1±29 2.9±16 1.9±13 1.0±6.5 0.53±5.6

* Number of measurements by position.

† Harmonic mean±Harmonic standard deviation.

a,b,c,d The same parameters show no difference between years.

x,y The same parameters show no difference between positions.

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REFERENCES

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