• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.169-178
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• 2020

The number of CT scans is increasing every year due to the improvement of the medical standards of the public, and thus the annual dose of medical radiation is also increasing. In this study, we evaluated the effective dose of the human body exposed to CT scans and estimated LAR. First, five region were selected from the CT diagnostic reference level guideline, and the effective dose of human body exposed to each examination was evaluated by clinical CT device. Second, the human organs and effective dose were calculated using the ALARA-CT program under the same conditions. Third, lifetime attributable risk (LAR) estimated by the effective dose exposed through the previous CT scan was estimated. As a result, the most effective dose was 21.18 mSv during the abdomen 4 phase scan, and the dose level was below DRL for all other tests except for the abdominal examination. As a result of evaluating effective dose using a dose calculation program under the same conditions, the results showed about 1.1 to 1.9 times higher results for each examination. In the case of organ dose, the closer the organ to the scan site, the higher the scattering ray. The lifetime attributable risk to CT radiation dose in adults was gradually decreased with age, and the results were somewhat different according to gender.

• Journal of radiological science and technology
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• v.33 no.3
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• pp.213-221
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• 2010

The Purpose of this study was to determine the effective dose to an average patient from Coronary Angiography (CA) and Percutaneous Coronary Intervention (PCI). And to estimate the lifetime attributable risk (LAR) of cancer associated with radiation exposure from CA and PCI. The dose-area product (DAP) values to the patient were recorded from 60 CA and 58 PCI. A Monte Carlo based program PCXMC was used to calculate the effective dose from DAP values for each patient. Lifetime attributable risks were estimated with models developed in the National Academies' Biological Effects of Ionizing Radiation VII report. The mean DAP values was $53.76\;Gy{\cdot}cm^2$ for CA and $165.82\;Gy{\cdot}cm^2$ for PCI. Mean effective dose were 1.28 mSv in CA, 3.94 mSv in PCI. Results of Calculate organ dose, lung doses was 2.17 mSv in CA and 6.71 mSv in PCI. Female breast doses was 5.45 mSv in CA and 16.82 mSv in PCI. LAR estimates for CA varied from 1 in 1,508 for man to 1 in 1,357 for women. In PCI procedure varied from 1 in 553 for man to 1 in 482 for women. DAP can be used as the dose indicator to calculate the organ dose and effective dose of patient based on Monte Carlo simulation. These dose estimates derived from our simulation models suggest that CA and PCI are associated with a nonnegligible LAR of cancer. This risk varies markedly and is considerably greater for women, PCI than for man, CA.

• Journal of Radiation Protection and Research
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• v.40 no.2
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• pp.118-123
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• 2015

The frequency of diagnostic radiation examinations in medical institutions has recently increased to 220 million cases in 2011, and the annual exposure dose per capita was 1.4 mSv, 51% and 35% respectively, compared to those in 2007. The number of chest radiography was found to be 27.59% of them, the highest frequency of normal radiography. In this study, we developed a shielding device to minimize radiation exposure by shielding areas of the body which are unnecessary for image interpretation, during the chest radiography. And in order to verify its usefulness, we also measured the difference in entrance surface dose (ESD) and the absorbed dose, before and after using the device, by using an international standard pediatric (10 years) phantom and a glass dosimeter. In addition, we calculated the effective dose by using a Monte Carlo simulation-based program (PCXMC 2.0.1) and evaluated the reduction ratio indirectly by comparing lifetime attributable risk of cancer incidence (LAR). When using the protective device, the ESD decreased by 86.36% on average, nasal cavity $0.55{\mu}Sv$ (74.06%), thyroid $1.43{\mu}Sv$ (95.15%), oesophagus $6.35{\mu}Sv$ (78.42%) respectively, and the depth dose decreased by 72.30% on average, the cervical spine(upper spine) $1.23{\mu}Sv$ (89.73%), salivary gland $0.5{\mu}Sv$ (92.31%), oesophagus $3.85{\mu}Sv$ (59.39%), thyroid $2.02{\mu}Sv$ (73.53%), thoracic vertebrae(middle spine) $5.68{\mu}Sv$ (54.01%) respectively, so that we could verify the usefulness of the shielding mechanism. In addition, the effective dose decreased by 11.76% from $8.33{\mu}Sv$ to $7.35{\mu}Sv$ before and after wearing the device, and in LAR assessment, we found that thyroid cancer decreased to male 0.14 people (95.12%) and female 0.77 people (95.16%) per one million 10-year old children, and general cancers decreased to male 0.14 people (11.70%) and female 0.25 people (11.70%). Although diagnostic radiation examinations are necessary for healthcare such as the treatment of diseases, based on the ALARA concept, we should strive to optimize medical radiation by using this shielding device actively in the areas of the body unnecessary for the diagnosis.