• Tuberculosis and Respiratory Diseases
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• 제86권4호
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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.

• 한국콘텐츠학회논문지
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• 제12권10호
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• pp.340-348
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• 2012

흉부영역에서 토모신테시스 검사의 유용성 평가를 위하여 흉부단순검사와 저 선량 CT, 토모신테시스를 실시하여 흡수선량을 비교하고 영상을 평가하였다. 흉부단순검사의 흡수선량은 $0.33{\pm}0.27$ mGy 이었으며, 저 선량 CT는 $1.26{\pm}0.56$ mGy, 토모신테시스는 $0.55{\pm}0.02$ mGy로 검사별 흡수선량 간에 유의한 차이를 보였다(p<0.001). 영상의 평가결과 단순검사 점수는 각각 $1.66{\pm}0.72$, $1.61{\pm}0.63$, $1.57{\pm}0.73$ 이었으며 저 선량 CT는 $2.92{\pm}0.26$, $2.91{\pm}0.29$, $2.88{\pm}0.32$ 이었고, 토모신테시스는 $2.69{\pm}0.51$, $2.76{\pm}0.43$, $2.66{\pm}0.61$로 검사에 따라 통계적으로 유의한 차이를 보였으나(p<0.001), 저 선량 CT와 토모신테시스 사이에는 유의한 차이를 보이지 않았다. 토모신테시스는 흉부영역의 검사 시 환자의 피폭선량을 최소화하고 진단의 효과를 높일 수 있는 유용한 검사라고 생각된다.

• Imaging Science in Dentistry
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• 제44권1호
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• pp.21-29
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• 2014

Purpose: To determine the conversion coefficients (CCs) from the dose-area product (DAP) value to effective dose in cone-beam CT. Materials and Methods: A CBCT scanner with four fields of view (FOV) was used. Using two exposure settings of the adult standard and low dose exposure, DAP values were measured with a DAP meter in C mode ($200mm{\times}179mm$), P mode ($154mm{\times}154mm$), I mode ($102mm{\times}102mm$), and D mode ($51mm{\times}51mm$). The effective doses were also investigated at each mode using an adult male head and neck phantom and thermoluminescent chips. Linear regressive analysis of the DAP and effective dose values was used to calculate the CCs for each CBCT examination. Results: For the C mode, the P mode at the maxilla, and the P mode at the mandible, the CCs were 0.049 ${\mu}Sv/mGycm^2$, 0.067 ${\mu}Sv/mGycm^2$, and 0.064 ${\mu}Sv/mGycm^2$, respectively. For the I mode, the CCs at the maxilla and mandible were 0.076 ${\mu}Sv/mGycm^2$ and 0.095 ${\mu}Sv/mGycm^2$, respectively. For the D mode at the maxillary incisors, molars, and mandibular molars, the CCs were 0.038 ${\mu}Sv/mGycm^2$, 0.041 ${\mu}Sv/mGycm^2$, and 0.146 ${\mu}Sv/mGycm^2$, respectively. Conclusion: The CCs in one CBCT device with fixed 80 kV ranged from 0.038 ${\mu}Sv/mGycm^2$ to 0.146 ${\mu}Sv/mGycm^2$ according to the imaging modes and irradiated region and were highest for the D mode at the mandibular molar.

• 핵의학기술
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• 제16권2호
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• pp.25-28
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• 2012

PET/CT에서의 환자의 피폭선량을 줄이기 위한 많은 연구가 진행되고 있다. 본 연구는 2012년 2월부터 2012년 3월까지 PET/CT검사를 위해 본원 핵의학과에 내원한 환자 149명(평균연령 $58{\pm}12.4$세)을 대상으로 하였고 장비는 Biograph True Point 40 (Siemens, USA)과 Gemini TF 64 (Philips, Cleveland)를 사용하였다. SIEMENS사의 Care Dose 4D를 사용하여 75명의 환자를 BMI 지수에 따라 세 집단으로 나누어 선량 감소율과 CTDI를 측정하였고 PHILIPS사의 D-dom을 이용하여 74명의 환자를 세 집단으로 나누어 선량 감소율과 CTDI를 측정하였다. 각 장비별로 세 집단 간의 측정값들이 유의한 차이를 보이는지 알아보기 위하여 SPSS Ver.18.0 통계분석프로그램을 이용하였다. 각각의 집단별로 평균값을 비교한 결과 Care Dose 4D를 사용했을 때 선량 감소율, CTDI 모두 p-value가 0.000으로서 통계적으로 유의한 차이가 있었다. D-dom을 사용했을 때 집단 간의 p-value는 선량 감소율 0.284, CTDI 0.226으로서 p>0.05이므로 집단 간의 유의한 차이가 없었다. 집단별로 평균 선량 감소율과 CTDI를 분석한 결과 Care Dose 4D를 사용했을 때 각각 정상집단에서 53.4%, 5.3 mGy, 과체중집단에서 49.5%, 5.8 mGy, 비만 집단에서 42.0%, 6.6 mGy로 나타났다. 반면에 D-dom을 사용하였을 때는 각각 정상 집단에서 22.7%, 4.5 mGy, 과체중 집단에서 22.1%, 4.6 mGy, 비만 집단에서 22.9%. 4.5 mGy로 나타났다. D-dom의 원리인 투사각도에 따른 선량조절은 환자의 비만도에 영향이 많지 않음을 알 수 있었다. 그리고 Care Dose 4D의 경우에는 투사각도에 따른 선량조절뿐만 아니라 환자 장축의 감쇠계수에 따른 선량조절, 환자 사이즈에 따른 선량조절 원리를 사용하고 있다. 그러므로 환자 장축의 감쇠계수에 따른 선량조절과 환자 크기에 따른 선량조절 원리가 환자의 비만도에 영향이 있다고 생각된다. 비록 같은 BMI 집단 간에 환자의 체형에 따른 오차가 있다고 여겨지지만, 앞으로 더욱더 많은 연구가 이루어진다면 Dose Modulation Technic이 PET/CT검사에서 환자의 피폭선량을 줄이는데 많은 도움이 될 것으로 생각된다.

• 한국의학물리학회지:의학물리
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• 제27권3호
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• pp.105-110
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• 2016

Sparse angular sampling has been studied recently owing to its potential to decrease the radiation exposure from computed tomography (CT). In this study, we investigated the analytic reconstruction algorithm in sparse angular sampling using the sinogram interpolation method for improving image quality and computation speed. A prototype of the spectral CT system, which has a 64-pixel Cadmium Zinc Telluride (CZT)-based photon-counting detector, was used. The source-to-detector distance and the source-to-center of rotation distance were 1,200 and 1,015 mm, respectively. Two energy bins (23~33 keV and 34~44 keV) were set to obtain two reconstruction images. We used a PMMA phantom with height and radius of 50.0 mm and 17.5 mm, respectively. The phantom contained iodine, gadolinium, calcification, and lipid. The Feld-kamp-Davis-Kress (FDK) with the sinogram interpolation method and Maximum Likelihood Expectation Maximization (MLEM) algorithm were used to reconstruct the images. We evaluated the signal-to-noise ratio (SNR) of the materials. The SNRs of iodine, calcification, and liquid lipid were increased by 167.03%, 157.93%, and 41.77%, respectively, with the 23~33 keV energy bin using the sinogram interpolation method. The SNRs of iodine, calcification, and liquid state lipid were also increased by 107.01%, 13.58%, and 27.39%, respectively, with the 34~44 keV energy bin using the sinogram interpolation method. Although the FDK algorithm with the sinogram interpolation did not produce better results than the MLEM algorithm, it did result in comparable image quality to that of the MLEM algorithm. We believe that the sinogram interpolation method can be applied in various reconstruction studies using the analytic reconstruction algorithm. Therefore, the sinogram interpolation method can improve the image quality in sparse-angular sampling and be applied to CT applications.

• 대한방사선기술학회지:방사선기술과학
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• 제44권5호
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• pp.473-480
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• 2021

This study was purpose to method that applies for improving the image quality in CT and X-ray scan, especially in the lung region. Also, we researched the parameters of the image before and after applying for Histogram Equalization (HE) such as mean, median values in the histogram. These techniques are mainly used for all type of medical images such as for Chest X-ray, Low-Dose Computed Tomography (CT). These are also used to intensify tiny anatomies like vessels, lung nodules, airways and pulmonary fissures. The proposed techniques consist of two main steps using the MATLAB software (R2021a). First, the technique should apply for the process of normalization for improving the basic image more correctly. In the next, the technique actively rearranges the intensity of the image contrast. Second, the Contrast Limited Adaptive Histogram Equalization (CLAHE) method was used for enhancing small details, textures and local contrast of the image. As a result, this paper shows the modern and improved techniques of HE and some advantages of the technique on the traditional HE. Therefore, this paper concludes that various techniques related to the HE can be helpful for many processes, especially image pre-processing for Machine Learning (ML), Deep Learning (DL).

• 한국의학물리학회지:의학물리
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• 제30권4호
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• pp.160-166
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• 2019

This study examined the clinical use of two newly installed computed tomography (CT) simulators in the Department of Radiation Oncology. The accreditation procedure was performed by the Korean Institute for Accreditation of Medical Imaging. An Xi R/F dosimeter was used to measure the CT dose index for each plug of the CT dose index phantom. Image qualities such as the Hounsfield unit (HU) value of water, noise level, homogeneity, existence of artifacts, spatial resolution, contrast, and slice thickness were evaluated by scanning a CT performance phantom. All test items were evaluated as to whether they were within the required tolerance level. CT calibration curves-the relationship between CT number and relative electron density-were obtained for dose calculations in the treatment planning system. The positional accuracy of the lasers was also evaluated. The volume CT dose indices for the head phantom were 22.26 mGy and 23.70 mGy, and those for body phantom were 12.30 mGy and 12.99 mGy for the first and second CT simulators, respectively. HU accuracy, noise, and homogeneity for the first CT simulator were -0.2 HU, 4.9 HU, and 0.69 HU, respectively, while those for second CT simulator were 1.9 HU, 4.9 HU, and 0.70 HU, respectively. Five air-filled holes with a diameter of 1.00 mm were used for assessment of spatial resolution and a low contrast object with a diameter of 6.4 mm was clearly discernible by both CT scanners. Both CT simulators exhibited comparable performance and are acceptable for clinical use.

• Tuberculosis and Respiratory Diseases
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• 제71권1호
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• pp.37-45
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• 2011

Background: Pulmonary emphysema (PE) is major cause of obstructive pulmonary function impairment (OPFI), which is diagnosed by spirometry. PE by high resolution CT is known to be correlated with OPFI. Recently, low dose CT (LDCT) has been increasingly used for screening interstitial lung diseases including PE. The aim of this study was to evaluate OPFI risks of subjects with PE detected by LDCT compared with those detected by simple digital radiography (SDR). Methods: LDCT and spirometry were administered to 266 inorganic dust exposed retired workers, from May 30, 2007 to August 31, 2008. This study was approved by our institutional review board and informed consent was obtained. OPFI risk was defined as less than 0.7 of forced expiratory volume in one second (FEV1)/forced vital capacity (FVC), and relative risk (RR) of OPFI of PE was calculated by multiple logistic regression analysis. Results: Of the 266 subjects, PE was found in 28 subjects (10.5%) by LDCT and in 11 subjects (4.1%) by SDR; agreement was relatively low (kappa value=0.32, p<0.001). FEV1 and FEV1/FVC were significantly different between PE and no PE groups determined by either SDR or LDCT. The differences between groups were larger when the groups were divided by the findings of SDR. When PE was present in either LDCT or SDR assays, the RRs of OPFI were 2.34 and 8.65, respectively. Conclusion: LDCT showed significantly higher sensitivity than SDR for detecting PE, especially low grade PE, in which pulmonary function is not affected. As a result, the OPFI risks in the PE group by LDCT was lower than that in the PE group by SDR.

• Tuberculosis and Respiratory Diseases
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• 제69권3호
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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.

• Asian Pacific Journal of Cancer Prevention
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• 제16권15호
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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.