• Tuberculosis and Respiratory Diseases
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• 제57권2호
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• pp.118-124
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• 2004

Lung cancer is the leading cause of cancer death for men and women in the industrialized world. It is desirable to detect disease at a stage when it is not causing symptoms and when control or cure is possible. If the screening test detects patients with the disease at an early stage, they can be examined to confirm the diagnosis and intervention can alter the natural history of the disease. The results of screening programs designed to detect early lung cancer using either conventional chest radiograph or sputum cytology are disappointing for a diagnostic screening test. Because of advances in helical CT imaging techniques, screening for lung cancer has been suggested as a possible method of improving outcome. Findings in recent publications suggest that substantial dose reduction is possible in chest CT. The advantages of low-dose CT are more sensitive than chest radiograph for detecting small pulmonary nodules that may be lung cancers, shorter scanning time than conventional chest CT scan without intravenous contrast injection, cheaper cost than standard CT, low radiation dose. However, the true clinical significance of the small tumors found by screening is still unknown, and their effect on mortality awaits future investigation. Furthermore, in addition to detecting an increased number of lung cancers, low-dose CT found at least one indeterminate nodule in many of all screened patients. The majority should be benign but evaluation of all these indeterminate nodules is not a trivial problem in routine practice. In conclusion, lung cancer screening with low-dose CT is a complex subject. The true effectiveness of lung cancer screening (a reduction in mortality from lung cancer) with low-dose CT can be determined through well-designed randomized control trials with enrolment of appropriate subjects.

• 대한방사선협회지
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• 제28권1호
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• pp.112-119
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• 2002

Purpose : The purpose of this study is to evaluate the usefulness, after we compare and analyze the difference about the location of a lesion and the result of diagnosis on chest radiographs(CR) and low dose computed tomography(LDCT) in subjects for healt

• 방사선산업학회지
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• 제11권3호
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• pp.131-137
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• 2017

To compare the radiation dose and image noise of low dose computed tomography (CT) and high resolution CT using the fixed tube current technique and automatic tube current modulation (CARE Dose 4D). Chest CT and human anthropomorphic phantom were used the RPL (radiophotoluminescence) dosimeters. For image evaluation, standard deviation of mean CT attenuation coefficient and CT attenuation coefficient was measured using ROI analysis function. The effective dose was calculated using CTDIvol and DLP. CARE Dose 4D was reduced by 74.7% and HRCT by 64.4% compared to the fixed tube current technique in low dose CT of chest phantom. In CTDIvol and DLP, the dose of CARE Dose 4D was reduced by fixed tube current technique. For effective dose, CARE Dose 4D was reduced by 47% and HRCT by 46.9% compared to the fixed tube current method, and the dose of CARE Dose 4D was significantly different (p<.05). Noise in the image was higher than that in the fixed tube current technique. Noise difference in the image of CARE Dose 4D in low dose CT was significant (p<.05). The low radiation dose and the noise difference of the CARE Dose 4D were compared with the fixed tube current technique in low dose CT and HRCT using chest phantom. The radiation doses using CARE Dose 4D were in accordance with the national and international dose standards. CARE Dose 4D should be applied to low dose CT and HRCT for clinical examination.

• Journal of Preventive Medicine and Public Health
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• 제55권3호
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• pp.273-279
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• 2022

Objectives: The aim of this study was to present the baseline results of a pilot project conducted to evaluate the effectiveness of lung cancer screening using low-dose chest computed tomography (CT) in regions with excessive radon levels in the Republic of Kazakhstan. Methods: In total, 3671 participants were screened by low-dose chest CT. Current, former, and never-smokers who resided in regions with elevated levels of radon in drinking water sources and indoor air, aged between 40 and 75 with no history of any cancer, and weighing less than 140 kg were included in the study. All lung nodules were categorized according to the American College of Radiology Lung Imaging Reporting and Data System (Lung-RADS 1.0). Results: Overall, 614 (16.7%) participants had positive baseline CT findings (Lung-RADS categories 3 and 4). Seventy-four cancers were detected, yielding an overall cancer detection rate of 2.0%, with 10.8% (8/74) stage I and a predominance of stage III (59.4%; 44/74). Women never-smokers and men current smokers had the highest cancer detection rates, at 2.9% (12/412) and 6.1% (12/196), respectively. Compared to never-smokers, higher odds ratios (ORs) of lung cancer detection were found in smokers (OR,2.48; 95% confidence interval [CI], 1.52 to 4.05, p<0.001) and former smokers (OR, 2.32; 95% CI, 1.06 to 5.06, p=0.003). The most common histologic type of cancer was adenocarcinoma (58.1%). Conclusions: Implementation of low-dose CT screening for lung cancer in regions with elevated radon levels is an effective method for both smokers and never-smokers.

• 대한방사선기술학회지:방사선기술과학
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• 제44권2호
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• pp.101-107
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• 2021

The purpose of this study was to evaluate optimal CT scan parameters to minimize patient dose to the irradiation and maintain satisfactory image quality in low-dose chest computed tomography (CT) scans. In a chest anthropomorphic phantom, chest CT scans were performed at different kVp and mA within reference of 3.4mGy in volume CT Dose Index (CTDI_vol). The following quantitative parameters had been statistically evaluated: image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and figure of merit (FOM). Nine radiographers conducted the blind test to select the optimal kVp-mA combination. Results indicated that the kVp-mA combination of 80kVp-90mA, 100kVp-50mA, 120kVp-30mA and 140kVp-30mA were obtained high SNR and CNR. The 120kVp-30mA combination offered good compromise in the FOM, which showed the quality and dose performance. In the blind test, an image of 80kVp-90mA obtained a high score with 4.7 points, and 120kVp-10mA or 140kVp-10mA with a low tube current were observed severe noise and poor image quality, thus resulting in decreased diagnostic accuracy. On the other hand, in the combination of high kVp and high mA(140kVp-90mA), the image quality was improved, but the radiation dose was also increased. the FOM value of 140kVp-90mA was lower than 120kVp-30mA. The application of appropriate scan parameters in low-dose chest CT scans produced satisfactory results in dose and image quality for the accuracy of the clinical diagnosis.

• Journal of Radiation Protection and Research
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• 제49권2호
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• pp.68-77
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• 2024

Background: Cone beam computed tomography (CBCT) is essential for correcting and verifying patient position before radiation therapy. However, it poses additional radiation exposure during CBCT scans. Therefore, this study aimed to evaluate radiological safety for the human body through dose assessment for CBCT. Materials and Methods: For CBCT dose assessment, the depth dose was evaluated using a cheese phantom, and the dose in the orbital area was evaluated using a human body phantom self-fabricated with a three-dimensional printer. Results and Discussion: The evaluation of radiation doses revealed maximum doses of 14.14 mGy and minimum doses of 6.12 mGy for pelvic imaging conditions. For chest imaging conditions, the maximum doses were 4.82 mGy, and the minimum doses were 2.35 mGy. Head imaging conditions showed maximum doses of 1.46 mGy and minimum doses of 0.39 mGy. The eyeball doses using a human body phantom model averaged at 2.11 mGy on the left and 2.19 mGy on the right. The depth dose ranged between 0.39 mGy and 14.14 mGy, depending on the change in depth for each imaging mode, and the average dose in the orbit area using a human body phantom was 2.15 mGy. Conclusion: Based on the experimental results, CBCT did not significantly affect the radiation dose. However, it is important to maintain a minimal radiation dose to optimize radiation protection following the as low as reasonable achievable principle.

• 한국방사선학회논문지
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• 제16권5호
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• pp.619-625
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• 2022

영상의학 분야에서 컴퓨터단층촬영(Computed Tomography, CT) 검사는 가장 보편화된 검사 방법 중의 하나이고 병원에서 이용 빈도가 매우 높은 검사 방법 중의 하나이다. 그러나 다른 검사 방법에 비해 매우 높은 방사선 피폭을 동반한다. 피폭 저감화를 위해서 CT 검사가 꼭 필요한 경우만 검사를 시행하는 방법과 꼭 필요해서 검사를 시행하는 경우에도 검사의 목적에 부합하고 적은 선량으로 검사를 시행할 수 있는 프로토콜을 사용해야 한다. 본 연구에서는 지역의 대표적 종합병원에서 사용하고 있는 가장 최신의 방사선량 사용정보를 알아보고 진단기준수준(Dignostic Reference Level, DRL)을 개발하고자 하였다. 실험결과 두부 CT, 복부 CT검사에서 DLP는 NRPB(U.K) 와 Korea DRL보다 높게 나타났다. 흉부 CT의 사용 DLP 값은 CT장치 3종 모두 낮게 나타났다. 해당 병원에서는 CT 검사 시 피폭 저감화를 위한 노력을 해야 하는 것을 알 수 있었고 특히 두부 CT, 복부 CT에서 피폭 저감의 노력이 필요하다고 판단한다.

• 방사선산업학회지
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• 제12권4호
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• pp.365-372
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• 2018

The use of CT examinations is increasing rapidly and radiation dose from CT examinations is much higher than other diagnostic radiography examinations including general radiography and mammography. DRLs used to optimize the radiation dose of patients by diagnostic radiology in each country. The objective of this study was to investigate and to analyze the status of DRLs from CT examinations in domestic and other countries. In other countries, DRLs were set for each age group and each examination considering the medical situation of each country. In Korea, DRLs were set for adults and children in 2017. For adults, DRLs were set for 13 examinations. Reported DLP values were 1119, 297, $472mGy{\cdot}cm$ for head, chest and abdomen pelvis examination, respectively. For children, DRLs were set for head examinations. Reported DLP values were 298 (0~1 years), 404 (2~5 years), 494 (6~10 years), 1,088 (11~15 years) $mGy{\cdot}cm$. DRLs of Korea were similar to other countries for head examinations. For chest examinations and abdomen pelvis examinations were relatively lower than other countries. As a major reason for relatively low radiation dose, it is considered to contribute the activity and management of medical radiation safety at national level.

• Tuberculosis and Respiratory Diseases
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• 제77권2호
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• pp.55-59
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• 2014

The US National Lung Screening Trial (NLST) demonstrated a 20% reduction in lung cancer mortality and a 6.7% decrease in all-cause mortality. The NLST is the only trial showing positive results in a high-risk population, such as in patients with old age and heavy ever smokers. Lung cancer screening using a low-dose chest computed tomography might be beneficial for the high-risk group. However, there may also be potential adverse outcomes in terms of over diagnosis, bias and cost-effectiveness. Until now, lung cancer screening remains controversial. In this review, we wish to discuss the evolution of lung cancer screening and summarize existing evidences and recommendations.

• 한국방사선학회논문지
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• 제16권4호
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• pp.411-417
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• 2022

본 연구에서는 저선량 흉부 CT 영상을 이용하여 VGGNet을 학습시키고 폐기종 검출 모델을 구현하고 성능을 확인하고자 한다. 연구에 사용된 저선량 흉부 CT 영상은 정상 진단 8000장, 폐기종 진단 3189장이며, 모델 학습을 위해 정상 데이터와 폐기종 데이터를 train, validation, test dataset으로 각각 60%, 24%, 16%로 무작위 추출하여 구분하였다. 학습을 위한 인공신경망은 VGGNet 중 VGG16과 VGG19를 사용하였으며, 학습이 완료된 모델 평가를 위해 정확도, 손실율, 오차 행렬, 정밀도, 재현율, 특이도, F1-score의 평가지표를 사용하였다. 폐기종 검출 정확도와 손실율은 VGG16과 VGG19 각각 92.35%, 95.88%, 0.21%, 0.09%, 정밀도는 91.60%, 96.55%, 재현율은 98.36%, 97.39%, 특이도는 77.08%, 92.72%, F1-score는 94.86%, 96.97%였다. 위의 평가지표를 통해 VGG19 모델의 폐기종 검출 성능이 VGG16 모델에 비해 우수하다고 판단된다. 본 연구를 통해 VGGNet과 인공신경망을 이용한 폐기종 검출 모델 연구에 기초자료로 사용할 수 있을 것으로 사료된다.