• Journal of Radiation Industry
• /
• v.7 no.2_3
• /
• pp.155-159
• /
• 2013

Late effects of chronic exposure to gamma radiation are potential hazards to worker in radiation facilities as well as to the general public. Recently, chronic gamma radiation exposure effects have become a serious concern. Using a total of 60 mice, we studied the biological effects of medium-dose chronic exposure to gamma radiation. Sixty female 6-week-old specific pathogen free Balb/c mice were randomly divided into six groups (five groups irradiated and one non-irradiated control group). Irradiation was carried out for 7 days using gamma rays at dose rates of 119.65, 238.10, 357.14, 476.19 and $595.24mGy\;h^{-1}$ with total doses 20, 40, 60, 80 and 100 Gy. After irradiation, we determined survival rate of gamma radiation exposed mice during 1 week and 476.19 and $595.24mGy\;h^{-1}$ exposed group mice showed less 10% of survival rate. Otherwise, 119.65, 238.10 and $357.14mGy\;h^{-1}$ exposed group mice were survived each 100%, 80% and 70%. Half of survived mice after 1 week are immediately sacrifice and counted body and spleen weights. Compared with control non-irradiated group, total body weights and spleen weights isolated from 119.65, 238.10 and 357.14 irradiated group mice showed significant decreased. However, no significant alteration was observed between 119.65, 238.10 and $357.14mGy\;h^{-1}$ irradiated group. Overall, our results show for the first time that medium-dose chronic gamma radiation has the potential to stimulation of biological effects.

• Journal of Radiation Protection and Research
• /
• v.41 no.4
• /
• pp.378-383
• /
• 2016

Background: Radiation dose rates in PRIDE facility is evaluated quantitatively for assessing radiation safety of workers because of large amounts of depleted uranium being handled in PRIDE facility. Even if direct radiation from depleted uranium is very low and will not expose a worker to significant amounts of external radiation. Materials and Methods: ORIGEN-ARP code was used for calculating the neutron and gamma source term being generated from depleted uranium (DU), and the MCNP5 code was used for calculating the neutron and gamma fluxes and dose rates. Results and Discussion: The neutron and gamma fluxes and dose rates due to DU on spherical surface of 30 cm radius were calculated with the variation of DU mass and density. In this calculation, an imaginary case in which DU density is zero was added to check the self-shielding effect of DU. In this case, the DU sphere was modeled as a point. In case of DU mixed with molten salt of 50-250 g, the neutron and gamma fluxes were calculated respectively. It was found that the molten salt contents in DU had little effect on the neutron and the gamma fluxes. The neutron and the gamma fluxes, under the respective conditions of 1 and 5 kg mass of DU, and 5 and $19.1g{\cdot}cm^{-3}$ density of DU, were calculated with the molten salt (LiCl+KCl) of 50 g fixed, and compared with the source term. As the results, similar tendency was found in neutron and gamma fluxes with the variation of DU mass and density when compared with source spectra, except their magnitudes. Conclusion: In the case of the DU mass over 5 kg, the dose rate was shown to be higher than the environmental dose rate. From these results, it is concluded that if a worker would do an experiment with DU having over 5 kg of mass, the worker should be careful in order not to be exposed to the radiation.

• Korean Journal of Environmental Biology
• /
• v.19 no.4
• /
• pp.270-277
• /
• 2001

To observe the stimulating effect of low dose ${\gamma}$ radiation on the dormancy breaking and growth, microtubers induced in vitro of two potato (Solanum tuberosum L. cv. Dejima and cv. Superior) cultivars with different storage duration were irradiated with ${\gamma}$ radiation at the dose of $0.5{\sim}30$ Gy. Sprouting rate, growth and tuber yield of ‘Dejima’ microtuber were increased by ${\gamma}$ radiation in the range of $2{\sim}16$ Gy. In the microtuber of ‘Superior’, the sprouting rate was promoted by 2 Gy and 4 Gy irradiation, and the growth and tuber yield by 0.5 Gy and 4 Gy irradiation. There were not that much difference in chlorophyll content of potato plantlet by the low dose ${\gamma}$ irradiation. These results suggested that low dose ${\gamma}$ radiation stimulated the dormancy breaking and potato growth.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.5
• /
• pp.996-1000
• /
• 2010

In order to apply VLC (visible light communication) in harsh environment of nuclear power plant in-containment building, the high luminance LEDs, which are key components of the VLC system, have been gamma irradiated at the dose rate of 4 kGy/h during 72 hours up to a total dose of 288 kGy. The radiation induced coloration effect in the high luminance LED bulb made of acryl or plastic material was observed. In the VLC wireless data transmission experiment using the high luminance LEDs irradiated by high dose rate gamma-ray, the radiation induced coloration effect of the high luminance LED bulb extended the communication distance compared to non-irradiated LEDs.

• Nuclear Engineering and Technology
• /
• v.12 no.3
• /
• pp.171-179
• /
• 1980

This paper presentss flux-to-dose conversion factors for neutrons and gamma-rays based on the concept of the maximum absorbed dose. Neutron flux-to-does-rate conversion factors for energies from 2.5$\times$10$^{-8}$ to 20 MeV are presented while the conversion factors for gamma-rays are given in the energy range of 0.01 to 15MeV. Flux-to-does-rate conversion factors, which were calculated under the assumption that the radiation energy distribution has nonlinearity in phantom, are different from those values obtained by monoenergetic radiation. Especially, these values obtained here were determined for the cross section libray such as DLC-23, DLC-27, and DLC-31. The flux-to-dose-rate conversion factors obtained in this work are in a good agreement with the values presented by American National Standard Institute (ANSI) N666. These results are used to calculate the dose rate distribution of neutron and gamma-ray in any radiation fields, and will be useful for the radiation shielding analysis, radiation protection and radiation dosimetry concerned with problems of continuous energy distribution.

• Korean Journal of Environmental Biology
• /
• v.17 no.3
• /
• pp.257-261
• /
• 1999

Effect of low dose gamma radiation on the growth of groundnut (Arachis hypognea L.) were investigated with respect to germination rate, seedling development and yield. Seeds of “Palpal” cultivar were irradiated with 0.5~20 Gy of ${\gamma}$ radiation in order to determine the hermetic effect of low dose radiation. The germination rate of ${\gamma}$-ray irradiation group was lower than that of the control but the seedling height of groundnut grown from seeds irradiated with low dose ${\gamma}$-ray was slightly higher than that of the control. The number of pod and kernels, and the seed yield increased by 27%, 17% and 19 %, respectively, in the 12.0 Gy irradiation group compared to that in the control group. The 100 seed weight was 87.2 g in the 4.0 Gy irradiation group, which was 11% heavier than 78.3 g in the control group. Low dose radiation showed an enhancement effects on the growth and yield components of groundnut.

• Journal of Radiation Industry
• /
• v.8 no.2
• /
• pp.89-95
• /
• 2014

This study was conducted to determine the optimal dose of gamma-ray on the growth and nucleus DNA damage for mutation breeding in licorice. Gamma-rays irradiated to dry seeds with various doses (0 to 1000 Gy). Significant decreases in germination rate (%), survival rate (%) and growth characteristics (plant height, number of leaves, root length and fresh weight) were observed by dose of increased. $LD_{50}$ (lethal dose) was approximately 400 Gy to 500 Gy. Also, reduction doses ($RD_{50}$) of plant height, number of leaves, root length and flash weight were 428 Gy, 760 Gy, 363 Gy and 334 Gy, respectively. It is supplest that the optimal dose of gamma irradiation for licorice mutation induction might be about 400 Gy in this study. We also conducted comet assay to observe nucleus DNA damage due to gamma irradiation. In comet assay, a clear difference was identified over 300 Gy treatments. With increasing doses of gamma-ray in the range of 100 to 1000 Gy, the rate of head DNA was decreased significantly from 92.88% to 73.09%. Tail length(${\mu}m$) was increased as the dose of increased over 300 Gy. Growth characteristics (Germination rate, Survival rate, plant height, number of leaves, root length and fresh weight) were highly negatively ($P{\leq}0.01$) correlated with dose. While the tail length was highly positively ($P{\leq}0.01$) correlated with dose.

• Progress in Medical Physics
• /
• v.32 no.4
• /
• pp.116-121
• /
• 2021

Purpose: To investigate the effects of dose rate on intensity-modulated radiation therapy (IMRT) quality assurance (QA). Methods: We performed gamma tests using portal dose image prediction and log files of a multileaf collimator. Thirty treatment plans were randomly selected for the IMRT QA plan, and three verification plans for each treatment plan were generated with different dose rates (200, 400, and 600 monitor units [MU]/min). These verification plans were delivered to an electronic portal imager attached to a Varian medical linear accelerator, which recorded and compared with the planned dose. Root-mean-square (RMS) error values of the log files were also compared. Results: With an increase in dose rate, the 2%/2-mm gamma passing rate decreased from 90.9% to 85.5%, indicating that a higher dose rate was associated with lower radiation delivery accuracy. Accordingly, the average RMS error value increased from 0.0170 to 0.0381 cm as dose rate increased. In contrast, the radiation delivery time reduced from 3.83 to 1.49 minutes as the dose rate increased from 200 to 600 MU/min. Conclusions: Our results indicated that radiation delivery accuracy was lower at higher dose rates; however, the accuracy was still clinically acceptable at dose rates of up to 600 MU/min.

• Journal of Radiation Industry
• /
• v.7 no.2_3
• /
• pp.135-139
• /
• 2013

Recently, chronic gamma radiation exposure on biological effects in middle dose-rates have become a serious concern. We investigated the biological effects of middle dose chronic exposure to gamma ray. Fifty male 6-week-old specific free Balb/c mice were randomly divided into five groups (four groups irradiated and one non-irradiated control group). Gamma radiation exposed in Gamma phytotron on Advanced Radiation Technology Institute (Jeongeup, Korea). Irradiation was carried out for 1 or 2 weeks using gamma rays at dose rates of 45 and $50mGy\;h^{-1}$ with total doses 7.56 Gy ($45mGy\;h^{-1}$, 1 week), 8.4 Gy ($50mGy\;h^{-1}$, 1 week), 15.12 Gy ($45mGy\;h^{-1}$, 2 weeks) and 16.8 Gy ($50mGy\;h^{-1}$, 2 weeks). After irradiation, immediately we sacrificed and counted body and organ weights. Moreover we counted spleen cell numbers. Compared with control non-irradiated group, all irradiated groups of body and spleen weights showed significant decreased. However, no significant alteration was observed between same irradiated period groups. In spleen cell numbers, reduced compared to the control group. However, significant alteration was observed between same irradiated period groups ($45mGy\;h^{-1}$, $50mGy\;h^{-1}$). These results demonstrated biological effects according to the radiation dose rate and irradiated period.

• Korean Journal of Environmental Biology
• /
• v.18 no.2
• /
• pp.247-253
• /
• 2000

In order to investigate the stimulatory effect(hormesis) of low dose gamma-radiation on the seeding growth of old seeds with respect to antioxidant defense systems, various doses of gamma radiation to the 5-year-old dried seeds of Chinese cabbage (Brassica campestris L. cv Sulin eockaei). Compared to the new, 1-year- old seeds, old seeds irradiated by low does gamma radiation in the range of 1-2 Gy showed vigor growth as revealed by statistically significant increases both in the germination rates and the leaf size and fresh weight. Further, seedlings grown from seeds treated by low dose gamma radiation showed higher peroxidase and catalase activities than non-treated seedlings. These results suggest that the antioxidant defense systems could be closely related to the stimulatory effects of low dose radiation. [antioxidant enzyme, chinese cabbage, gamma radiation, germination rate, hormesis]