• Tuberculosis and Respiratory Diseases
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• v.69 no.3
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• pp.177-183
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• 2010

Background: Smoking reduces pulmonary function and induces various lung diseases. Recently, the rate of emphysema detection has increased due to lung cancer screening with low-dose chest computed tomography (CT). The purpose of this study was to evaluate changes in lung function associated with emphysema in healthy smokers. Methods: One hundred and ninety one healthy smokers, who had undergone a low-dose chest CT (LDCT) scan as part of lung cancer screening and had revisited the health center after a median 23.9 months' time, were recruited into this study. The severity of emphysema was calculated by the direct observation of a radiologist and a pulmonologist indipendently. Longitudinal changes in lung function according to emphysema based on LDCT and type of smoker was analyzed. Results: Of the participants in this study, 25% of healthy smokers had emphysema, which was mild in severity, in older patients (p=0.003) and in heavy smokers (p<0.001). $FEV_1/FVC$ and FEF25-75% were decreased in current smokers with emphysema (p=0.001 and p=0.009, respectively) and without emphysema (p=0.001 and p=0.042). Although lung function was not decreased in ex-smokers without emphysema, $FEV_1/FVC$ and FEF25-75% were decreased in ex-smoker with emphysema (p=0.020 and p=0.010). Conclusion: Upon examination with LDCT, the prevalence of emphysema was higher in healthy smokers was than in non-smokers. Lung function was diminished in smokers with emphysema, in spite of former smoker.

• Journal of The Korean Radiological Technologist Association
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• v.28 no.1
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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

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6293-6298
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• 2015

Opportunistic screening for lung cancer is commonly conducted in Korea in accordance with physician recommendations and screenee's preferences. However, studies have yet to thoroughly examine the public's understanding of the risks posed by lung cancer screening. This study was conducted to assess changes in intentions to undergo lung cancer screening in response to being informed about exposure to radiation during low-dose computed tomography (LDCT) tests and to identify factors with the greatest influence thereon among Korean men. We conducted sub-group interviews among men chosen from the 2013 Korea National Cancer Screening Survey (KNCSS), a nationwide, population-based, cross-sectional survey of men aged 40 to 74 years and women aged 30 to 74 years. From 4100 participants in the KNCSS, 414 men who underwent any cancer screening test within the last 2 years were randomly selected for inclusion in this study. Via face-to-face interviews, their intentions to undergo lung cancer screening were assessed before and after being informed about exposure to radiation during LDCT testing. Of the 414 participants, 50% were current smokers. After receiving information on the benefits of the test, 95.1% stated an intention to undergo screening; this decreased to 81.6% after they received information on the harms of the test. The average decrease in intention rate was 35.3%. Smoking status, household income, and education level were not associated with lowered intentions to undergo lung cancer screening. Participants who were older than 60 years old (OR=0.56; 95% CI= 0.33-0.96) and those with less concern for radiation exposure (OR=0.56; 95% CI=0.36-0.89) were less likely to lower their screening intentions. The results of this study suggest that there is a need to educate both non-smokers and former smokers on the harms of lung cancer screening.

• Korean Journal of Radiology
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• v.19 no.6
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• pp.1179-1186
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• 2018

Objective: The purposes of this study were to evaluate size-specific dose estimate (SSDE) of low-dose CT (LDCT) in the Korean Lung Cancer Screening (K-LUCAS) project and to determine whether CT protocols from Western countries are appropriate for lung cancer screening in Korea. Materials and Methods: For participants (n = 256, four institutions) of K-LUCAS pilot study, volume CT dose index ($CTDI_{vol}$) using a 32-cm diameter reference phantom was compared with SSDE, which was recalculated from $CTDI_{vol}$ using size-dependent conversion factor (f-size) based on the body size, as described in the American Association of Physicists in Medicine Report 204. This comparison was subsequently assessed by body mass index (BMI) levels (underweight/normal vs. overweight/obese), and automatic exposure control (AEC) adaptation (yes/no). Results: Size-specific dose estimate was higher than $CTDI_{vol}$ ($2.22{\pm}0.75mGy$ vs. $1.67{\pm}0.60mGy$, p < 0.001), since the f-size was larger than 1.0 for all participants. The ratio of SSDE to $CTDI_{vol}$ was higher in lower BMI groups; 1.26, 1.37, 1.43, and 1.53 in the obese (n = 103), overweight (n = 70), normal (n = 75), and underweight (n = 4), respectively. The ratio of SSDE to $CTDI_{vol}$ was greater in standard-sized participants than in large-sized participants independent of AEC adaptation; with AEC, SSDE/$CTDI_{vol}$ in large- vs. standard-sized participants: $1.30{\pm}0.08$ vs. $1.44{\pm}0.08$ (p < 0.001) and without AEC, $1.32{\pm}0.08$ vs. $1.42{\pm}0.06$ (p < 0.001). Conclusion: Volume CT dose index based on a reference phantom underestimates radiation exposure of LDCT in standard-sized Korean participants. The optimal radiation dose limit needs to be verified for standard-sized Korean participants.

• Tuberculosis and Respiratory Diseases
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• v.86 no.4
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• pp.284-293
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• 2023

Background: Attitudes towards smoking, lung cancer screening, and perceived risk of lung cancer have not been widely studied in Malaysia. The primary objective of this study was to describe the factors affecting the willingness of high-risk current smokers and ex-smokers to undergo low-dose computed tomography (LDCT) screening for lung cancer. Methods: A prospective, cross-sectional questionnaire study was conducted in current smokers or ex-smokers aged between 55 and 80 years at three hospitals in Kota Kinabalu, Sabah, Malaysia. The questionnaire recorded the following parameters: perceived lung cancer risk; Prostate Lung Colon Ovarian Cancer 2012 risk prediction model excluding race and ethnicity predictor (PLCO_m2012norace); demographic characteristics; psychosocial characteristics; and attitudes towards lung cancer and lung cancer screening. Results: A vast majority of the 95 respondents (94.7%) indicated their willingness to undergo screening. Stigma of lung cancer, low levels of knowledge about lung cancer symptoms, concerns about financial constraints, and a preference for traditional medication were still prevalent among the respondents, and they may represent potential barriers to lung cancer screening uptake. A desire to have an early diagnosis (odds ratio [OR], 11.33; 95% confidence interval [CI], 1.53 to 84.05; p=0.02), perceived time constraints (OR, 3.94; 95% CI, 1.32 to 11.73; p=0.01), and proximity of LDCT screening facilities (OR, 14.33; 95% CI, 1.84 to 111.4; p=0.01) had significantly higher odds of willingness to undergo screening. Conclusion: Although high-risk current smokers and ex-smokers are likely to undergo screening for lung cancer, several psychosocial barriers persist. The results of this study may guide the policymakers and clinicians regarding the need to improve lung cancer awareness in our population.

• Journal of Korea Multimedia Society
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• v.23 no.6
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• pp.729-737
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• 2020

Screening with low-dose spiral computed tomography (LDCT) has been shown to reduce lung cancer mortality by about 20% when compared to standard chest radiography. One of the problems arising from screening programs is that large amounts of CT image data must be interpreted by radiologists. To solve this problem, automated detection of pulmonary nodules is necessary; however, this is a challenging task because of the high number of false positive results. Here we demonstrate detection of pulmonary nodules using six off-the-shelf convolutional neural network (CNN) models after modification of the input/output layers and end-to-end training based on publicly databases for comparative evaluation. We used the well-known CNN models, LeNet-5, VGG-16, GoogLeNet Inception V3, ResNet-152, DensNet-201, and NASNet. Most of the CNN models provided superior results to those of obtained using customized CNN models. It is more desirable to modify the proven off-the-shelf network model than to customize the network model to detect the pulmonary nodules.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.6
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• pp.2480-2496
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• 2020

Considering that high-dose X-ray radiation during CT scans may bring potential risks to patients, in the medical imaging industry there has been increasing emphasis on low-dose CT. Due to complex statistical characteristics of noise found in low-dose CT images, many traditional methods are difficult to preserve structural details effectively while suppressing noise and artifacts. Inspired by the deep learning techniques, we propose a densely connected residual network (DCRN) for low-dose CT image noise cancelation, which combines the ideas of dense connection with residual learning. On one hand, dense connection maximizes information flow between layers in the network, which is beneficial to maintain structural details when denoising images. On the other hand, residual learning paired with batch normalization would allow for decreased training speed and better noise reduction performance in images. The experiments are performed on the 100 CT images selected from a public medical dataset-TCIA(The Cancer Imaging Archive). Compared with the other three competitive denoising algorithms, both subjective visual effect and objective evaluation indexes which include PSNR, RMSE, MAE and SSIM show that the proposed network can improve LDCT images quality more effectively while maintaining a low computational cost. In the objective evaluation indexes, the highest PSNR 33.67, RMSE 5.659, MAE 1.965 and SSIM 0.9434 are achieved by the proposed method. Especially for RMSE, compare with the best performing algorithm in the comparison algorithms, the proposed network increases it by 7 percentage points.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.261-267
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• 2017

The study has attempted to evaluate and compare the image evaluation and exposure dose by respectively applying filter back projection (FBP), the existing test method, and adaptive statistical iterative reconstruction (ASIR) with different values of tube voltage during the low dose computed tomography (LDCT). With the image reconstruction method as basis, chest phantom was utilized with the FBP and ASIR set at 10%, 20% respectively, and the change of tube voltage (100 kVp, 120 kVp). For image evaluation, back ground noise, signal-noise ratio (SNR) and contrast-noise ratio (CNR) were measured, and, for dose assessment, CTDIvol and DLP were measured respectively. In terms of image evaluation, there was significant difference in ascending aorta (AA) SNR and inpraspinatus muscle (IM) SNR with the different amount of tube voltage (p < 0.05). In terms of CTDIvol, the measured values with the same tube voltage of 120 kVp were 2.6 mGy with no-ASIR and 2.17 mGy with 20%-ASIR respectively, decreased by 0.43 mGy, and the values with 100 kVp were 1.61 mGy with no-ASIR and 1.34 mGy with 20%-ASIR, decreased by 0.27 mGy. In terms of DLP, the measured values with 120 kVp were $103.21mGy{\cdot}cm$ with no-ASIR and $85.94mGy{\cdot}cm$ with 20%-ASIR, decreased by $17.27mGy{\cdot}cm$ (about 16.7%), and the values with 100 kVp were $63.84mGy{\cdot}cm$ with no-ASIR and $53.25mGy{\cdot}cm$ with 20%-ASIR, a decrease by $10.62mGy{\cdot}cm$ (about 16.7%). At lower tube voltage, the rate of dose significantly decreased, but the negative effects on image evaluation was shown due to the increase of noise.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.71-75
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• 2013

Purpose: Currently, decrement revision using LDCT is used in PET/CT. But cold artifacts are often found in decrement revision image by mismatch between LDCT image and Emission image near diaphragm due to patient's respiration. This research studied reduction of cold artifact by patient's respiration using CTAC Shift among revision methods. Materials and Methods: From March to September in 2012, 30 patients who had cold artifacts by respiration were targeted using PET/CT Discovery 600 (GE Healthcare, MI, USA) equipment. Patients with cold artifacts were additionally scan in diaphragm area, and the image shown cold artifacts at whole body test were revised using CTAC Shift. Cold artifacts including image, additional scan image and CTAC Shift revision image were evaluated as 1~5 points with naked eye by one nuclear medicine expert, 4 radiotechnologists with over 5 year experience. Also, standard uptake value of 3 images was compared using paired t-test. Results: Additional scan image and CTAC Shift revision image received relatively higher score in naked eye evaluation than cold artifacts including image. The additional scan image and CTAC Shift revision image had high correlation as the results of ANOVA test of standard uptake value and did not show significant difference. Conclusion: When cold artifacts are appeared by patient's respiration at PET/CT, it causes not only patient inconvenience but troubles in test schedule due to extra radiation exposure and time consumption by additional scan. But if CTAC Shift revision image can be acquired with out additional scan, it is considered to be helped in exact diagnosis without unnecessary extra radiation exposure and additional scan.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.214-227
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• 2013

Computed tomographic scan as a screening procedures in asymptomatic individuals has seen a steady increase with the introduction of multiple-raw detector CT scanners. This report provides a brief review of the current controversy surrounding CT cancer screening, with a focus on the radiation induced cancer risks and clinical efficacy. 1. A large study of patients at high risk of lung cancer(the National Lung Screening Trial[NLST]) showed that CT screening reduced cancer deaths by 20%(1.33% in those screened compared with 1.67% in those not screened). The rate of positive screening tests was 24.2% and 96.4% of the positive screening results in the low-dose CT group were false-positive. Radiation induced lung cancer risk was estimated the most important in screening population because ERR of radiation induced lung cancer does not show the decrease with increasing age and synergistic connection between smoking and radiation risk. Therefore, the radiation risk may be on the same order of magnitude as the benefit observed in the NLST. Optimal screening strategy remain uncertain, CT lung cancer screening is not yet ready for implementation. 2. Computed tomographic colonography is as good as colonoscopy for detecting colon cancer and is almost as good as colonoscopy for detecting advanced adenomas, but significantly less sensitive and specific for smaller lesions and disadvantageous for subsequent therapeutic optical colonoscopy if polyps are detected. The average effective dose from CT colonography was estimated 8-10 $mS{\nu}$, which could be a significant dose if administered routinely within the population over many years. CT colonography should a) achieve at least 90% sensitivity and specificity in the size category from 6 and 10 mm, b) offer non-cathartic bowl preparation and c) be optimized and standardized CT parameters if it is to be used for mass screening. 3. There is little evidence that demonstrates, for whole-body scanning, the benefit outweighs the detriment. This test found large portion of patient(86~90.8%) had at least one abnormal finding, whereas only 2% were estimated to have clinically significant disease. Annual scans from ages 45 to 75 years would accrue an estimated lifetime cancer mortality risk of 1.9%. There is no group within the medical community that recommends whole-body CT. No good studies indicate the accuracy of screening CT, at this time. The benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established. These areas need further research. Therefore wild screening should be avoided.