Comparison of Image Quality using Various Quantitative Evaluation Methods between Sequence and Spiral scan during Brain CT

손인철(In-Chul Son),이기백(Ki-Baek Lee) 대한CT영상기술학회 2020 대한CT영상기술학회지 Vol.22 No.2

두부 CT검사에는 고식적 방식과 나선형 방식이 있다.두부 CT검사 시 고식적 방식이 나선형 방식에 비해 화질이 더 우수하여 더 많이 사용되어왔다. 그러나 이러한 우수한 화질이라는 평가는 주로 정성적으로 평가한 것이 대부분이었으며 이는 객관성이 떨어진다는 제한점이 있다. 이에 본 연구는 다량한 정량적 평가를 하기 위하여 고식적 방식과 나선형 방식, 즉 2가지 검사방법을 동시에 시행한 적이 있는 환자 20명을 대상으로 CT Number, 영상 잡음, 대조도 대 잡음비 등 다양한 정량적 평가를 하였다. 또한 저대조도, 영역백질, 회백(질)의 구분을 위하여 ACR 팬텀의 모듈 2를 관전류초를 변화시키며 히스토그램 및 그래프를 이용해 두부 CT 영상 화질을 비교하였다. 후향적 환자 연구 시 CT Number, 영상 잡음, 대조도 대 잡음비 각각의 결과는 고식적 방식과 나선형 방식 순서로 31.73 ± 3.96 vs 31.92 ± 3.25, 3.53 ± 0.63 vs 4.1 ± 0.54, 275.82 ± 43.49 vs 239.76 ± 31.88이었다. 팬텀 연구의 경우 고식적 스캔 방식이 나선형 스캔 방식에 비해 보고자 하는 CT Number를 잘 표현했고 그래프화하였을 때 높은 첨도를 가지고 있었다. 결과적으로 고식적 방식이 나선형 방식에 비하여 우수한 화질을 가졌고, 히스토그램 기반으로 분석한 수치와 그래프를 이용한 방법은 영상 평가의 도구로 사용 시 유용할 수 있을 것이라 판단된다. There are two scan methods such as sequence and spiral scan in CT examination.I n Brain CT, the sequence scan mode has been utilized more than the spiral mode due to having better image quality.H owever, this evaluation of image quality was mainly subjective assessment and had some limitation.S o, we tried to analyze the image quality of brain CT between the sequence and spiral mode with 20 patients data and an ACR phantom by using various quantitative evaluation such as CT number, image noise, contrast to noise ratio (CNR), and histogram-based analysis.E ach result of CT number, image noise, CNR between two modes (Sequence vs Spiral) were as follows: 31.73 ± 3.96 vs 31.92 ± 3.25, 3.53 ± 0.63 vs 4.1 ± 0.54, 275.82 ± 43.49 vs 239.76 ± 31.88. Overall quantitative image quality of the sequence mode were better than the spiral mode in the study of patient images.A lso, histogram analysis by using the ACR phantom represented higher figures of targeted CT number in the sequence mode than the spiral mode. Additionally, all graphs of phantom images with the sequence scan had high profiles.A s a results, the sequence scan mode had better quantitative image quality and histogram based evaluation was proven by very useful method to distinguish the low contrast resolution between different two vague portions.

A Study on Establishment of Basic Safety and Essential Performance Criteria of Mobile Computed Tomography

김은혜(Eun Hye Kim),박혜민(Hye Min Park),김정민(Jung Min Kim) 대한방사선과학회(구 대한방사선기술학회) 2021 방사선기술과학 Vol.44 No.3

As the number of Coronavirus Disease-19 (COVID-19) patients increases in a global pandemic situation, the usefulness of mobile computed tomography (CT) is gaining attention. Currently, mobile CT follows the basic safety and essential performance evaluation criteria of whole-body or limited-view X-ray CT in order to obtain device approval and evaluation in the Republic of Korea. Unlike stationary CT, mobile CT is not operated in shielded areas but rather areas such as intensive care units, operating rooms, or isolation rooms. Therefore, it requires a different basic safety and essential performance evaluation standard than stationary CT. In this study, four derived basic safety evaluation criteria related to electrical, mechanical, and radiation safety were included (dose indication test, protection against stray radiation, safety measures against excessive X-rays, half-value layer measurement); and seven essential performance evaluation criteria were included (tube voltage accuracy, mAs accuracy, radiation dose reproducibility, CT number of water, noise, uniformity, and spatial resolution); total eleven basic safety and essential performance evaluation criteria were selected. This study aims to establish appropriate basic safety and essential performance evaluation criteria for simultaneously obtaining images with diagnostic value and reducing the exposure of nearby patients, medical staff, and radiologic technologists during the use of mobile CT.

기관-기관지연화증 환자에서 CT상 중심 기관지의 정량화

임원형,진공용,한영민,김은영 대한영상의학회 2016 대한영상의학회지 Vol.74 No.5

Purpose: To know which factors help to diagnose tracheobronchomalacia (TBM) using CT quantification of central airway. Materials and Methods: From April 2013 to July 2014, 19 patients (68.0 ± 15.0 years; 6 male, 13 female) were diagnosed as TBM on CT. As case-matching, 38 normal subjects (65.5 ± 21.5 years; 6 male, 13 female) were selected. All 57 subjects underwent CT with end-inspiration and end-expiration. Airway parameters of trachea and both main bronchus were assessed using software (VIDA diagnostic). Airway parameters of TBM patients and normal subjects were compared using the Student t-test. Results: In expiration, both wall perimeter and wall thickness in TBM patients were significantly smaller than normal subjects (wall perimeter: trachea, 43.97 mm vs. 49.04 mm, p = 0.020; right main bronchus, 33.52 mm vs. 42.69 mm, p < 0.001; left main bronchus, 26.76 mm vs. 31.88 mm, p = 0.012; wall thickness: trachea, 1.89 mm vs. 2.22 mm, p = 0.017; right main bronchus, 1.64 mm vs. 1.83 mm, p = 0.021; left main bronchus, 1.61 mm vs. 1.75 mm, p = 0.016). Conclusion: Wall thinning and decreased perimeter of central airway of expiration by CT quantification would be a new diagnostic indicators in TBM. 목적: 흉부 CT에서 기관-기관지연화증의 중심 기관지 정량화를 통해 어떤 인자가 이 질환의 진단에 관여하는지 알아보고자 하였다. 대상과 방법: 2013년 4월부터 2014년 7월까지 흉부 CT에서 기관-기관지연화증으로 진단받은 19명(68.0 ± 15.0세; 남자 6명, 여자 13명)과 정상인 38명(65.5 ± 21.5세; 남자 6명, 여자 13명)을 대상으로 하였다. CT는 호기와 흡기 말에 시행하였으며 각각의 영상에 대해서 기관과 좌우 기관지를 정량화하였다. 두 그룹에서 내강 둘레의 평균값, 벽의 평균 두께를 Student t-test를 이용하여 비교하였다. 결과: 호기 시에 기관-기관지연화증 환자의 중심 기관지 내강 둘레의 평균값이 정상군에 비해 더 작았다(기관: 43.97 mm vs. 49.04 mm, p = 0.020; 우측 주 기관지: 33.52 mm vs. 42.69 mm, p < 0.001; 좌측 주 기관지: 26.76 mm vs. 31.88 mm, p = 0.012). 기도 벽의 평균 두께 또한 환자군이 정상군에 비해 더 얇았다(기관: 1.89 mm vs. 2.22 mm, p = 0.017; 우측 주 기관지: 1.64 mm vs. 1.83 mm, p = 0.021; 좌측 주 기관지: 1.61 mm vs. 1.75 mm, p = 0.016). 결론: 중심 기관지의 CT 정량화를 통해, 호기 시의 기도 내강 둘레 감소와 벽의 두께 감소가 기관-기관지연화증 진단의 새로운 지표가 될 수 있다.

Four-Dimensional CT of the Diaphragm in Children: Initial Experience

구현우 대한영상의학회 2018 Korean Journal of Radiology Vol.19 No.1

Objective: To evaluate the technical feasibility of four-dimensional (4D) CT for the functional evaluation of the pediatric diaphragm. Materials and Methods: In 22 consecutive children (median age 3.5 months, age range 3 days−3 years), 4D CT was performed to assess diaphragm motion. Diaphragm abnormalities were qualitatively evaluated and diaphragm motion was quantitatively measured on 4D CT. Lung density changes between peak inspiration and expiration were measured in the basal lung parenchyma. The diaphragm motions and lung density changes measured on 4D CT were compared between various diaphragm conditions. In 11 of the 22 children, chest sonography was available for comparison. Results: Four-dimensional CT demonstrated normal diaphragm (n = 8), paralysis (n = 10), eventration (n = 3), and diffusely decreased motion (n = 1). Chest sonography demonstrated normal diaphragm (n = 2), paralysis (n = 6), eventration (n = 2), and right pleural effusion (n = 1). The sonographic findings were concordant with the 4D CT findings in 90.9% (10/11) of the patients. In diaphragm paralysis, the affected diaphragm motion was significantly decreased compared with the contralateral normal diaphragm motion (-1.1 ± 2.2 mm vs. 7.6 ± 3.8 mm, p = 0.005). The normal diaphragms showed significantly greater motion than the paralyzed diaphragms (4.5 ± 2.1 mm vs. -1.1 ± 2.2 mm, p < 0.0001), while the normal diaphragm motion was significantly smaller than the motion of the contralateral normal diaphragm in paralysis (4.5 ± 2.1 mm vs. 7.6 ± 3.8 mm, p = 0.01). Basal lung density change of the affected side was significantly smaller than that of the contralateral side in diaphragm paralysis (89 ± 73 Hounsfield units [HU] vs. 180 ± 71 HU, p = 0.03), while no significant differences were found between the normal diaphragms and the paralyzed diaphragms (136 ± 66 HU vs. 89 ± 73 HU, p = 0.1) or between the normal diaphragms and the contralateral normal diaphragms in paralysis (136 ± 66 HU vs. 180 ± 71 HU, p = 0.1). Conclusion: The functional evaluation of the pediatric diaphragm is feasible with 4D CT in select children.

마이크로 포커스 X-ray CT를 이용한 콘크리트 손상균열의 정량적 평가

정자혜 ( Jahe Jung ) 대한지질공학회 2018 지질공학 Vol.28 No.3

본 연구에서는 치핑작업중에 콘크리트에 발생할 수 있는 손상균열을 정량분석하기 위해 X-ray CT 이미지를 이용하는 방법을 제안하고자 한다. 이를 위해 치핑작업을 수행한 후, 균열이 발생한 콘크리트 블록을 코어링하여 직경 50 mm, 길이 100 mm의 시편을 준비하였다. 그 후 마이크로 포커스 X-ray CT 촬영을 하여 얻은 이미지를 3D 이미지로 재구성(reconstruction)하였다. 이렇게 얻어진 3D CT 이미지에 3DMA (3 Dimensional Medial axis Analysis)법을 적용하여, 손상 평가 파라메타로 시편의 위치에 따라 균열의 성질을 평가하여 손상을 분석하였다. 분석결과 치핑에 의한 손상은 치핑 표면으로부터 3 cm 깊이까지 발생한 것으로 나타났다. 또한 CT이미지 공간분석법에서 사용되는 여러 파라메타 중 공극률 지표(Porosity index), Burn number 그리고 Medial axis 의 파라메타를 이용해 치핑표면 근처의 손상 분석이 가능하다는 것이 확인되었다. 이 방법은 내부구조에 변화가 발생한 암석을 대상으로 한 연구에서도 비파괴 상태로 내부의 균열 평가, 가시화에 적용가능하다. This study developed a method to quantitatively measure the size of cracks in concrete using X-ray CT images. We prepared samples with a diameter of 50 mm and a length of 100 mm by coring cracked concrete block that was obtained by chipping. We used a micro-focus X-ray CT, then applied the 3DMA method (3 Dimensional Medial axis Analysis) to the 3D CT images to find effective parameters for damage assessment. Finally, we quantitatively assessed the damage based on sample locations, using the damage assessment parameter. Results clearly show that the area near the chipping surface was damaged to a depth of 3 cm. Furthermore, X-ray methods can be used to evaluate the porosity index, burn number, and medial axis, which are used to estimate the damage to the area near the chipping surface.

복부-골반 CT검사 시 피폭선량 최적화에 관한 프로토콜 연구

홍동희(Dong Hee Hong) 대한방사선과학회(구 대한방사선기술학회) 2017 방사선기술과학 Vol.40 No.2

복부-골반 CT검사 시 피폭선량을 측정해 보고, 영상 판독에 영향을 미치지 않는 범위에서 복부와 골반의 피폭선량 최적화를 위한 프로토콜을 제시하고자 하였다. 기존 임상의 스캔 방식인 120 kVp, AEC(auto exposure control) 기법을 이용한 복부-골반을 1 phase로 스캔을 하였고, 새로 제시한 2 phase 스캔 방식은 1 phase 복부검사와 2 phase 골반검사로 각각 나누어 복부검사는 관전압 120 kVp, AEC, 골반검사는 120 kVp, 100, 150, 200, 250, 300, 350, 400 mA로 고정 관전류 기법을 이용하여 실시하였다. 스캔 시 측정된 CTDIVOL, DLP 값을 이용해 선량값을 비교하였고, 각 스캔 영상에서 CT 감약계수와 노이즈, SNR의 평균값을 구해 영상을 평가하였다. 연구결과는 2 phase 스캔 시 1 phase 스캔 시보다 CTDIVOL 값은 복부에서 26%, 골반 100∼250 mA에서 1.8∼59.5% 감소, 300∼400 mA에서 12.7∼30% 증가로 유의한 차이를 보였다. 또한, DLP값은 2 phase 스캔 시 1phase 스캔 시보다 복부에서 약 53%, 골반에서 약 41∼81% 감소를 보였으나 통계적으로 유의하지 않았다. SNR은 심장주변에서 2 phase 스캔 시, 골반주변에서는 1 phase 스캔 시, 상복부와 하복부에서 1 phase 스캔 시보다 2phase 200∼250 mA 스캔 시 높게 나타났다. 또한, CT Number와 노이즈는 전반적으로 비슷한 양상을 보였지만, 골반 주변에서 노이즈가 높게 나타났다. 그러나 2 phase의 골반주변 250 mA 스캔 시 1 phase와 비슷한 노이즈값을 나타냈고 통계적으로 유의한 차이를 보이지 않았기에 통상적인 1 phase 400 mA보다 골반을 분리시켜 250 mA 스캔 시 화질에 차이 없이 피폭선량 감소효과를 볼 수 있을 것으로 본다. 그러므로 잦은 복부-골반 CT를 시행하는 환자 혹은 가임기여성, 소아의 골반은 피폭을 줄이면서 화질차이 없이 검사를 위한 2 phase 검사를 제안한다. This study measured the exposure dose during abdominal-pelvic CT exam which occupies 70% of CT exam and tried to propose a protocol for optimized exposure dose in abdomen and pelvis without affecting the imagery interpretation. The study scanned abdomen-pelvis using the current clinical scan method, the 120 kVp, auto exposure control(AEC), as 1 phase. As for the newly proposed 2 phase scan method, the study divided into 1 phase abdomen exam and 2 phase pelvis exam and each conducted tube voltage 120 kVp, AEC for abdomen exam, and fixed tube current method in 120 kVp, 100, 150, 200, 250, 300, 350, 400 mA for pelvis exam. The exposure dose value was compared using CTDIVOL, DLP value measured during scan, and average value of CT attenuation coefficient, noise, SNR from each scan image were obtained to evaluate the image. As for the result, scanning of 2 phase showed significant difference compared to 1 phase. In CTDIVOL value, the 2 phase showed 26% decrease in abdomen, 1.8∼59.5% decrease in pelvis for 100∼250 mA, 12.7%∼30% increase in pelvis for 300∼400 mA. Also, DLP value showed 53% decrease in abdomen and 41∼81% decrease in pelvis when scanned by 2 phase compared to 1 phase, but it was not statistically significant. As for the SNR, when scanning 2 phase close to heart, scanning 1 phase close to pelvis, scanning and scanning 1 phase at upper and lower abdomen, it was higher when scanning 2 phase for 200∼ 250 mA. Also, the CT number and noise was overall similar, but the noise was high close to pelvis. However, when scanning 2 phase for 250 mA close to pelvis, the noise value came out similar to 1 phase, and did not show statistically significant difference. It seems when separating pelvis to scan in 250 mA rather than 400 mA in 1 phase as before, it is expected to have reduced effect of exposure dose without difference in the quality of image. Thus, for patients who often get abdominal-pelvic CT exam, fertile women or children, this study proposes 2 phase exam for smaller exposure dose with same image quality.

연구논문 : 정책평가방법의 비교분석: 표시,광고규제를 중심으로

최신애 ( Shin Ae Choi ),여정성 ( Jung Sung Yeo ) 한국조사연구학회 2010 조사연구 Vol.11 No.3

본 연구는 정책평가방법에 따라 표시·광고규제의 정책성과에 대한 평가결과를 비교분석하였다. 이를 위해 우리나라 표시·광고규제의 주요정책인 중요정보고시제도, 표시광고실증제도, 임시중지명령제도, 정정광고제도를 평가대상으로 선정하였다. 그리고 소비자 관점의 전문가와 기업의 표시·광고업무 실무자, 공정거래위원회에서 소비자정책을 담당하는 전·현직 공무원 등 총 76명을 직접 방문하여 구조화된 설문지와 병행하여 면접법으로 자료를 수집하였다. 본 연구의 결과 정책성과에 대한 평가방법에 따라 기업의 표시·광고업무 실무자들과 정책담당자들의 정책별 평가순위에 소폭의 변동이 있었으며, 기존의 일반적인 단순평가 결과는 ``문항의 중요도``를 반영한 가중평가와 ``판단에 대한 확신성``을 고려한 퍼지평가에 비해 상향된 평가점수가 산출되었다. 이는 정책성과 평가에 있어 어떠한 평가방법을 사용하는가에 따라 평가결과가 다르게 나타날 수 있음을 시사한다. This study evaluated the policy performance of i) Public Notice of Critical Information, ii) Substantiation of Facts in Labeling and Advertising, iii) Temporary Injunctions, and iv) Advertisement Correcting Misrepresented Facts, which were main policies belonged to Fair Labeling and Advertising Act(hereinafter referred to as "FLA Act"). The data was collected by visiting 76 persons personally, who were consumer policy and law experts, labeling and advertising staffs of corporations, and persons in charge of policies including public officials dealing with consumer policies at Korea Fair Trade Commission, while using a structured questionnaire at the same time. The survey was performed to examine the general policy performance and evaluation the results of FLA Act by evaluation methods. The results of the analysis are comprehensively summarized as follows. There were differences in the ranking of policies evaluated by labeling and advertising staffs of corporations and persons in charge of policies according to evaluation methods, and, in Simple Evaluation, higher scores were gained compared to Weighted Evaluation which reflected weighted values or Fuzzy Evaluation. The result shows that evaluation results can vary in policy performance evaluation according to evaluation methods.

반복적 연산으로 얻은 Sparse-view CT 영상에 대한 정량적 평가

김혜선,조민형,이수열,Kim, H.S.,Gao, Jie,Cho, M.H.,Lee, S.Y. 대한의용생체공학회 2011 의공학회지 Vol.32 No.3

Sparse-view CT imaging is considered to be a solution to reduce x-ray dose of CT. Sparse-view CT imaging may have severe streak artifacts that could compromise the image qualities. We have compared quality of sparseview images reconstructed with two representative iterative reconstruction techniques, SIRT and TV-minimization, in terms of image error and edge preservation. In the comparison study, we have used the Shepp-Logan phantom image and real CT images obtained with a micro-CT. In both phantom image and real CT image tests, TV-minimization technique shows the best performance in error reduction and preserving edges. However, the excessive computation time of TV-minimization is a technical challenge for the practical use.

Is FDG -PET-CT A Valuable Tool in Prediction of Persistent Disease in Head and Neck Cancer

Uzel, Esengul Kocak,Ekmekcioglu, Ozgul,Elicin, Olgun,Halac, Metin,Uzel, Omer Erol Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.8

Objectives: To evaluate accuracy of FDG-PET CT in prediction of persistent disease in head and neck cancer cases and to determine prognostic value of metabolic tumor response. Materials and Methods: Between 2009 and 2011, 46 patients with squamous cell carcinoma of head and neck receiving PET-CT were treated with definitive radiotherapy, with or without chemotherapy. There were 29 nasopharyngeal, 11 hypopharyngeal, 3 oropharyngeal and 3 laryngeal cancer patients, with a median age of 50.5 years (range 16-84), 32 males and 14 females. All patients were evaluated with PET-CT median 3-5 months (2.4-9.4) after completion of radiotherapy. Results: After a median 20 months of follow up, complete metabolic response was observed in 63% of patients. Suspicious residual uptake was present in 10.9% and residual metabolic uptake in 26.0% of patients. The overall sensitivity, specificity, positive predictive value and negative predictive value of FDG-PET-CT for detection of residual disease was 91% and 81%, 64% and 96% respectively. Two year LRC was 95% in complete responders while it was 34% in non-complete responders. Conclusions: FDG PET CT is a valuable tool for assessment of treatment response, especially in patients at high risk of local recurrence, and also as an indicator of prognosis. Definitely more precise criteria are required for assessment of response, there being no clear cut uptake value indicating residual disease. Futhermore, repair processes of normal tissue may consume glucose which appear as increased uptake in control FDG PET CT.

문화콘텐츠 경쟁력평가를 위한 산업플랫폼 제안에 대한 연구

허식,박현승 한국경영교육학회 2013 경영교육연구 Vol.28 No.2

Recently a cultural contents industry is drawing attention as a new growth engine of the Korean economy. This study is to propose an alternative industrial classification system reflecting the current tendency of the cultural contents industry. The present classification system in the cultural contents area is not reflecting the fine arts as well as the technological aspect. These are very important components for the competitiveness achievement of the cultural contents industry. Through expert surveys and internal reviews, we suggest twelve major industries and forty-nine 2-digit industries(called the industrial platform). Our industrial classification system suggested is expected to be partly helpful to evaluate the competitiveness level on the cultural contents area. 최근 문화콘텐츠산업은 창의성ㆍ예술성을 기반으로 한 문화콘텐츠와 더불어 기술측면에서 CT(culture technology)의 중요성이 매우 증가하는 추세이다. 그러나 현행 문화콘텐츠산업 분류체계는 창의성ㆍ예술성이 강조되는 순수예술 분야가 포함되어 있지 않고, 산업적 측면과 기술적 측면이 동시에 고려되지 않아 산업경쟁력 확보차원에서 이를 재구성할 필요가 있다. 본 연구에서는 기존의 문화콘텐츠와 순수예술로 양분되어 있는 두 영역을 통합하고, CT의 활용확대에 따른 환경변화를 고려한 새로운 산업플랫폼을 제안하고자 한다. 이를 위해 기존분류체계 분석, 문헌조사, 전문가 설문을 통한 범주설정, 내부검토 등의 과정을 거쳐, 순수예술을 포함한 12개 대분류와 CT를 반영한 중분류로서 49개의 산업플랫폼을 제안하였다. 또한 어떤 부문에서 경쟁력이 확보되어 있는지를 평가할 수 있도록 새로운 산업플랫폼과 CT의 기술측면이 반영된 매트릭스구조를 예시하였다. 본 연구는 CT의 발전에 맞추어 산업과 기술간 융합이 제대로 반영된 문화콘텐츠 산업플랫폼을 제시함으로써 산업의 경쟁력 평가에 상당한 도움이 될 것으로 기대된다.