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

doi:10.14316/pmp.2016.27.3.146

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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

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.

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

REFERENCES

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Fig. 1.

Annual collective dose of radiation workers by position between 2011 and 2015.

Fig. 2.

Annual average of the spatial dose rate by position between 2011 and 2015.

Fig. 3.

Annual average of the surface contamination by position between 2011 and 2015.

Table 1.

Annual average effective dose distribution by position between 2011 and 2015.

Position	mSv
Position	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

Table 2.

Number of workers exceeding the mean effective dose in their position between 2011 and 2015.

Position	2011		2012		2013		2014		2015
Position	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.

Table 3.

Mean and standard deviation of the depth dose and surface dose between 2011 and 2015.

Year	N^*	Mean±S.D.^†
Year	N^*	Deep dose	Shallow dose
2011	292	0.70±1.7^a	0.78±2.1^a
2012	335	0.80±1.9^a	0.89±2.3^a
2013	372	0.63±1.6^a,b	0.72±2.3^a,b
2014	386	0.62±1.7^a,b	0.64±1.6^a,b
2015	446	0.42±1.3^c	0.45±1.5^c
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.

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.

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±2.0^a,x	196	0.98±2.2^a,x	214	0.77±1.9^a,b,x	216	0.77±1.8^a,b,x	248	0.53±1.4^b,x
F	110	0.37±1.1^a,y	139	0.56±1.2^a,y	158	0.44±1.2^a,b,y	170	0.43±1.4^a,b,y	198	0.29±1.1^b,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±2.3^a,x	196	1.1±2.8^a,x	214	0.91±2.8^a,b,x	216	0.82±1.9^a,b,x	248	0.57±1.8^b,x
F	110	0.42±1.4^a,y	139	0.58±1.2^a,y	158	0.45±1.2^a,b,y	170	0.42±1.3^a,b,y	198	0.29±1.1^b,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.

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±3.71^a,x	14±55^a,x,y	4.3±31^a,y^,z	1.3±6.8^a,y^,z	0.66±1.6^a^,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±13^b,x	0.24±0.56^b,x,y	2.0±5.5^b,y^,z	0.30±1.6^b,y^,z	0.26±0.33^b^,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±5.5^c,x	2.0±5.5^c,x,y	2.3±8.0^c,y^,z	2.3±5.9^c,y^,z	3.5±28^c^,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±3.6^c,x	1.0±2.8^c,x,y	1.0±2.8^c,y^,z	0.89±2.5^c,y^,z	0.51±1.2^c^,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±0.34^d,x	0.43±1.9^d,x,y	0.34±0.73^d,y^,z	0.30±0.30^d,y^,z	0.25±0.20^d^,z
Total	N	3200	5207	5018	5587	5126
Total	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.

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±1.4^b,x	0.03±0.18^c,x	0.03±0.24^d,x	0.01±0.05^d,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±2.0^a,x	0.82±3.3^b,x	0.30±1.8^c,x	0.55±4.1^d,x	0.43±1.9^d,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±0.53^a,x	0.88±12^b,x	0.05±0.33^c,x	0.11±1.9^d,x	0.05±0.82^d,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±45^a,y	7.1±24^b,y	5.4±22^c,y	2.5±10^d,y	1.2±9.6^d,y
Total	N	2961	4982	4590	5170	4664
Total	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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