• Journal of Radiation Protection and Research
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• v.44 no.1
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• pp.26-31
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• 2019

Background: Stereotactic ablative radiotherapy (SABR) plans in prostate cancer are compared and analyzed to investigate the low magnetic effect (0.35 T) on the dose distribution, with various dosimetric parameters according to low magnetic field. Materials and Methods: Twenty patients who received a 36.25 Gy in five fractions using the MR-IGRT system (ViewRay) were studied. For planning target volume (PTV), the point mean dose ($D_{mean}$), maximum dose ($D_{max}$), minimum dose ($D_{min}$) and volumes receiving 100% ($V_{100%}$), 95% ($V_{95%}$), and 90% ($V_{90%}$) of the total dose. For organs-at-risk (OARs), the differences compared using $D_{max}$, $V_{50%}$, $V_{80%}$, $V_{90%}$, and $V_{100%}$ of the rectum; $D_{max}$, $V_{50%}$, $V_{30Gy}$, $V_{100%}$ of the bladder; and $V_{30Gy}$ of both left and right femoral heads. For both the outer and inner shells near the skin, $D_{mean}$, $D_{min}$, and $D_{max}$ were compared. Results and Discussion: In PTV analysis, the maximum difference in volumes ($V_{100%}$, $V_{95%}$, and $V_{90%}$) according to low magnetic field was $0.54{\pm}0.63%$ in $V_{100%}$. For OAR, there was no significant difference of dose distribution on account of the low magnetic field. In results of the shells, although there were no noticeable differences in dose distribution, the average difference of dose distribution for the outer shell was $1.28{\pm}1.08Gy$ for $D_{max}$. Conclusion: In the PTV and OARs for prostate cancer, there are no statistically-significant differences between the plan calculated with and without a magnetic field. However, we confirm that the dose distribution significantly increases near the body shell when a magnetic field is applied.

• Journal of the Korean Society of Radiology
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• v.10 no.7
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• pp.495-502
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• 2016

In this study, we analyzed the effects of radiation exposure, as compared to the hematological parameters change of medical radiation workers and the public. The mean value of all hematological parameters were in the normal range. Eosin mean value of the radiation workers($2.52{\pm}1.79%$) showed that a significantly lower than the control group($2.92{\pm}1.39%$). In the comparison of the results depending on the occupation period, it showed high value that the mean of the radiation workers group WBC, platelet, Lymph, Mono, Baso. Over 20 years of radiation workers WBC, Mono showed low values and less than 10 years of radiation workers mean value of Baso showed low values, there was no statistical significance. In the comparison of the results depending on the 4 years cumulative radiation dose, Over 5.0 mSv of Radiation works RBC($4.61{\pm}0.53$ vs $4.91{\pm}0.38$), Hct($41.51{\pm}4.07$ vs $43.97{\pm}3.40$), Eosin($1.74{\pm}1.14$ vs $2.92{\pm}1.39$) showed low value, it was statistical significance. 0.5~1.0 mSv radiation exposure workers Hb ($13.93{\pm}1.75$) showed a significantly lower value than that of the control group ($14.90{\pm}1.29$).

• The Journal of Korean Society for Radiation Therapy
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• v.1 no.1
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• pp.23-28
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• 1985

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.868-869
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• 2005

• Nuclear Engineering and Technology
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• v.40 no.7
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• pp.539-550
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• 2008

Lung cancer is the most prevalent global cancer, ${\sim}90%$ of which is caused by cigarette smoking. The LNT hypothesis has been inappropriately applied to estimate lung cancer risk due to ionizing radiation. A threshold of ${\sim}1\;Gy$ for lung cancer has been observed in never smokers. Lung cancer risk among nuclear workers, radiologists and diagnostically exposed patients was typically reduced by ${\sim}40%$ following exposure to <100 mSv low LET radiation. The consistency and magnitude of reduced lung cancer in nuclear workers and occurrence of reduced lung cancer in exposed non-worker populations could not be explained by the HWE. Ecologic studies of indoor radon showed highly significant reductions in lung cancer risk. A similar reduction in lung cancer was seen in a recent well designed case-control study of indoor radon, indicating that exposure to radon at the EPA action level is associated with a decrease of ${\sim}60%$ in lung cancer. A cumulative whole-body dose of ${\sim}1\;Gy$ gamma rays is associated with a marked decrease in smoking-induced lung cancer in plutonium workers. Low dose, low LET radiation appears to increase apoptosis mediated removal of $\alpha$-particle and cigarette smoke transformed pulmonary cells before they can develop into lung cancer.

• Journal of Radiation Protection and Research
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• v.6 no.1
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• pp.1-7
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• 1981

This report presents the results of the environmental radiation program at Korea Advanced Energy Research Institute (KAERI) ($37^{\circ}38'N,\;127^{\circ}05'E$) and its surroundings for the last two decades (January, 1961 through December, 1980). In the 1960s, the monthly mean levels of environmental external radiation encountered ranged from a low of 14.2 microroentgen per hour to a high of 42.2 microroentgen per hour with a mean of 21.7 microroentgen per hour, while in 1970s it ranged from a low of 12.4 microroentgen per hour to a high of 40.8 microroentgen per hour with a mean of 20.4 microroentgen per hour. It may, therefore, be said that environmental radiation dose rates remained almost unchanged for the two decades except for the second half of 1960s and the first half of 1970s during which the off-site and on-site patterns were frequently unlike in form and intensity with appreciable differences between average values. Particular results of interest with respect to the effects of the fallout gamma dose rate on environmental radiation show that elevated levels were encountered in association with the deposits of fresh debris from Chinese and Russian nuclear weapons tests in particular.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.1
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• pp.1-6
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• 2020

The purpose of this study is to analyze the radiation dose data of the space crew of the flight crew and to present a plan for the health management of the flight crew on the basis of the analysis. The analysis show that the average exposure dose of the flight attendants continued to rise, and the exposure dose of the flight attendants was five(5) times higher than that of the radiation workers. As a way to reduce the effects of cosmic radiation, this paper suggests appropriate personnel allocation by model, balanced allocation of high and low latitude routes by crew according to the aircraft type, and a low altitude flight plan for high latitude flight. This study will help aviation crew members understand cosmic radiation and trust in the company's policies. In the future, it will be necessary to enhance the flight safety of the crew by deriving meaningful results by analyzing data related to cosmic radiation of various routes.

• Nuclear Engineering and Technology
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• v.40 no.7
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• pp.551-560
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• 2008

Radiation has stochastic aspects in its generation, its choice of interaction mode during traveling in media, and its impact on living bodies. In certain circumstances, like in high dose environments resulting from low-LET radiation, the variance in its impact on a target volume is negligible. On the contrary, in low dose environments, especially when they are attributed to high-LET radiation, the impact on the target carries with it a large variance. This variation is more significant for smaller target volumes. Microdosimetric techniques, which have been developed to estimate the distribution of radiation energy deposited to cellular and subcellular-sized targets, contrast with macrodosimetric techniques which count only the average value. Since cells and DNA compounds are the critical targets in human bodies, microdosimetry, or dose estimation by microscopic approach, helps one better analyze the biological effects of radiation on the human body. By utilizing microbeam systems designed for individual cell irradiation, scientists have discovered that human cells exhibit radiosensitive reactions without being hit themselves (bystander effect). During the past 10 or more years, a new therapeutic protocol using discontinuous multiple micro-slit beams has been investigated for its clinical application. It has been suggested that the beneficial bystander effect is the essence of this protocol.

• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3943-3948
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• 2022

Single-photon emission computed tomography is one of the reliable pin-by-pin verification techniques for spent-fuel assemblies. One of the challenges with this technique is to increase the total fuel assembly verification speed while maintaining high verification accuracy. The aim of the present study, therefore, was to develop an artificial intelligence (AI) algorithm-based tomographic image analysis technique for partial-defect verification of fuel assemblies. With the Monte Carlo (MC) simulation technique, a tomographic image dataset consisting of 511 fuel-rod patterns of a 3 × 3 fuel assembly was generated, and with these images, the VGG16, GoogLeNet, and ResNet models were trained. According to an evaluation of these models for different training dataset sizes, the ResNet model showed 100% pattern estimation accuracy. And, based on the different tomographic image qualities, all of the models showed almost 100% pattern estimation accuracy, even for low-quality images with unrecognizable fuel patterns. This study verified that an AI model can be effectively employed for accurate and fast partial-defect verification of fuel assemblies.

• Progress in Medical Physics
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• v.28 no.1
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• pp.27-32
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• 2017

We investigated the effect of a commercial iterative reconstruction technique (iDose, Philips) on the image quality and the dose calculation for the treatment plan. Using the electron density phantom, the 3D CT images with five different protocols (50, 100, 200, 350 and 400 mAs) were obtained. Additionally, the acquired data was reconstructed using the iDose with level 5. A lung phantom was used to acquire the 4D CT with the default protocol as a reference and the low dose (one third of the default protocol) 4D CT using the iDose for the spine and lung plans. When applying the iDose at the same mAs, the mean HU value was changed up to 85 HU. Although the 1 SD was increased with reducing the CT dose, it was decreased up to 4 HU due to the use of iDose. When using the low dose 4D CT with iDose, the dose change relative to the reference was less than 0.5% for the target and OARs in the spine plan. It was also less than 1.1% in the lung plan. Therefore, our results suggests that this dose reduction technique is applicable to the 4D CT image acquisition for the radiation treatment planning.