• 한국방사선학회논문지
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• 제12권1호
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• pp.65-70
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• 2018

CT 장치는 물체 내부의 단면 영상 획득이 가능하기 때문에 여러 분야에 광범위하게 사용되고 있다. 단면 영상을 획득하는 여러 단계의 에러 요인들로 인해 다양한 아티팩트가 유발되고 있다. 장치에 의해 발생하는 링 아티팩트를 조사하였다. $512{\times}512$ 크기의 수치 팬텀을 구현하고 대수적 재구성 기법으로 링 아티팩트의 특성을 연구하였다. 프로그램은 Visual C++로 작성하였으며 720개의 투영 및 1,280개의 검출기 픽셀을 갖는 상황에서 구현하였다. 링 아티팩트는 검출기 픽셀의 검출 효율이 서로 달라서 발생한다는 것을 확인하였다. Ring Value 값이 증가할수록 Ring Intensity의 값도 증가하였고, 영상의 원점에 가까울수록 링 아티팩트가 강하게 나타났다. 단면 영상에서 링 아티팩트가 발생하는 위치를 파악하고 역으로 검출기 픽셀의 위치를 추적해 검출효율을 보정함으로써 링 아티팩트를 제거할 수 있을 것이다.

• 한국의학물리학회지:의학물리
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• 제17권4호
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• pp.207-211
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• 2006

kV cone-beam CT (CBCT)가 결합된 선형가속기의 등장으로 더욱 정확한 영상유도 방사선치료(Image-guided radiation therapy, IGRT)가 가능해졌다. IGRT는 영상장비를 이용해 표적의 이동을 보정할 수 있는 방사선치료기술로, CBCT를 이용한 IGRT의 경우 내부 장기의 정보를 바탕으로 병변의 이동을 정확히 알 수 있다. 내부 장기의 정보를 얻기 위해서는 방사선이 조사되기 바로 전에 환자의 CBCT 영상을 획득하여 치료계획 시 사용한 모의치료 CT영상과 정합을 수행하게 된다. 본 연구에서는 CBCT 영상의 재구성 품질에 따른 정합결과를 비교해 보았다. 6명의 환자로부터 총 56개의 CBCT 투과 정보를 획득하여 분석한 결과, 평행이동벡터의 차가 1 mm를 초과하는 경우는 단 3개에 불과하였다. 회전이동의 경우, x, y, z, 세 축을 모두 고려하였으며, 그 결과 총 168 ($56{\times}3$)개에서 단 3개만이 $1^{\circ}$ 이상의 차이를 나타냈다.

• 대한방사선기술학회지:방사선기술과학
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• 제46권2호
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• pp.99-106
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• 2023

The height of the table should be considered important during computed tomography (CT) examination, but according to previous studies, not all radiology technologists set the table at the patient's center at the examination, which affects the exposure dose and image quality received by the patient. Therefore, this study intends to study the image quality exposure dose according to the height of the table to realize the optimal image quality and dose during the brain CT scan. The head phantom images were acquired using Philips Brilliance iCT 256. When the image was acquired, the table height was adjusted to 815, 865, 915, 965, 1015, and 1030 mm, respectively, and each scan was performed 3 times for each height. For the exposure dose measurement, optically stimulated luminescence dosimeter (OSLD) was attached to the front, side, eye, and thyroid gland of the head phantom. In the signal to noise ratio (SNR) measurement result, The SNR values for each table height were all lower than 915 mm. As a result of exposure dose, the exposure dose on each area increased as the table height decreased. The height of the table has a close relationship with the patient's radiation exposure dose in the CT scan.

• Korean Journal of Radiology
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• 제20권5호
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• pp.729-738
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• 2019

Objective: To assess the effects of iterative model reconstruction (IMR) on image quality for demonstrating non-calcific high-risk plaque characteristics of coronary arteries. Materials and Methods: This study included 66 patients (53 men and 13 women; aged 39-76 years; mean age, 55 ± 13 years) having single-vessel disease with predominantly non-calcified plaques evaluated using prospective electrocardiogram-gated 256-slice CT angiography. Paired image sets were created using two types of reconstruction: hybrid iterative reconstruction (HIR) and IMR. Plaque characteristics were compared using the two algorithms. The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the images and the CNR between the plaque and adjacent adipose tissue were also compared between the two reformatted methods. Results: Seventy-seven predominantly non-calcified plaques were detected. Forty plaques showed napkin-ring sign with the IMR reformatted method, while nineteen plaques demonstrated napkin-ring sign with HIR. There was no statistically significant difference in the presentation of positive remodeling, low attenuation plaque, and spotty calcification between the HIR and IMR reconstructed methods (all p > 0.5); however, there was a statistically significant difference in the ability to discern the napkin-ring sign between the two algorithms (χ² = 12.12, p < 0.001). The image noise of IMR was lower than that of HIR (10 ± 2 HU versus 12 ± 2 HU; p < 0.01), and the SNR and CNR of the images and the CNR between plaques and surrounding adipose tissues on IMR were better than those on HIR (p < 0.01). Conclusion: IMR can significantly improve image quality compared with HIR for the demonstration of coronary artery and atherosclerotic plaques using a 256-slice CT.

• 한국임상수의학회지
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• 제22권4호
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• pp.431-434
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• 2005

A 2-year-old castrated male, Cocker spaniel dog with a history of chronic productive cough for 2 to 3 months and with unsuccessful treatment was referred to Veterinary Medical Teaching Hospital, Seoul National University. On thoracic radiographs, there were alveolar infiltrations at left cranial and right caudal lung fields, and soft-tissue opacity round to oval images at overall lung field. The bronchi were dilated, tortuous and not tapered. Abnormal air was accumulated focally in the caudodorsal lung fields. To scrutinize the soft-tissue opacity image and accumulated air, computed tomography (CT) was done. On CT images, severe cylindrical or tubular bronchiectasis was confirmed. And the soft-tissue opacity images were found in the dilated bilated and thought to complexes of mucous plugs, inflammatory cells, necrotic and fibrotic tissue. The dog was dead next day to the CT scan, so necropsy and histopathologic examination were perfermed. On the histopathology, there were cylindrical bronhiectasis and severe diffuse chronic fibrinous necropurulent bronchitis and bronchopneumonia. In this case, it was difficult to diagnose the bronchiectasis only with radiography due to the concurrent lesions, such as pulmonary infiltrations and mucous plugs, which was identified by computed tomography. Thus, computed tomography is considered as a useful modality to confirm tile bronchiectasis camouflaged by the concurrent lesion.

• 한국콘텐츠학회논문지
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• 제17권6호
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• pp.81-85
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• 2017

본 연구는 컴퓨터단층촬영을 이용한 요로결석 검사에서 저선량 CT(Low dose Computed Tomography) 프로토콜의 적용에 따른 유용성을 평가하였다. 연구대상은 2016년 6월-12월까지 부산지역 일개 의료기관을 내원한 비뇨기계 환자이며 연구에 이용된 프로토콜은 통계적 반복 재구성법(Adaptive Statistical Iterative Reconstruction, ASIR)을 50% 적용한 저선량 CT 프로토콜이다. 정량적 분석 결과 횡단면상(Axial image)의 신장의 관심 영역(region of image. ROI) 내 평균 화소 값과 표준편차는 복부촬영 프로토콜 $26.21{\pm}7.08$, 저선량 CT 프로토콜 $20.03{\pm}8.16$이며 관상면(Coronal imalge) 영상에서 신장의 관심영역 내 평균 화소 값과 표준편차는 복부촬영 프로토콜 $22.07{\pm}7.35$, 저선량 CT 프로토콜 $21.67{\pm}6.11$이었다. 정성적 분석결과 인공물에 대한 4명의 관찰자 평균값은 복부촬영 프로토콜 $19.14{\pm}0.36$, 저선량 CT 프로토콜 $19.17{\pm}0.43$이며 해상도 및 대조도의 평균값은 복부촬영 프로토콜 $19.35{\pm}0.70$, 저선량 CT 프로토콜 $19.29{\pm}0.58$이었다. 피폭선량 분석 결과 복부촬영 프로토콜의 CTDIvol 평균값은 18.02 mGy, DLP 평균값은 $887.51mGy{\cdot}cm$이며 저선량 CT 프로토콜 CTDIvol 평균값은 7.412 mGy, DLP 평균값은 $361.22mGy{\cdot}cm$이었다. 이로 인한 선량의 감소율은 각 58.82%, 59.29% 이었다.

• Journal of Oral Medicine and Pain
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• 제41권2호
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• pp.41-47
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• 2016

Purpose: The purpose of this study was to analyze the size and morphology of mandibular condyle and mandibular fossa between temporomandibular joint (TMJ) disc displacement (DD) patients and healthy subjects using cone-beam computed tomography (CBCT). Methods: Twenty healthy subjects and twenty TMJ DD patients participated in this study respectively. We made five measurements in mandibular condyle (medio-lateral dimension, antero-posterior dimension, condyle height, intercondylar distance and intercondylar angle) and two measurements in mandibular fossa (mandibular fossa depth and articular eminence angle) using CBCT image. Results: There was no difference between two groups in medio-lateral dimension. In case of antero-posterior dimension, average of healthy controls was larger than that of TMJ DD patients, but that was not significant statistically. There were no significant differences between two groups in condyle height. Comparing intercondylar distance and intercondylar angle between two groups, there was no significant difference between two groups. In comparison of mandibular fossa depth and articular eminence angle, there was no significant difference between two groups. Conclusions: We couldn't find any definite relationship between TMJ morphology and TMJ DD.

• Imaging Science in Dentistry
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• 제46권1호
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• pp.39-45
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• 2016

The incidental finding of an enlarged mastoid foramen on the right posterior mastoid region of temporal bone is reported, together with a discussion of its clinical significance. A 67-year-old female underwent the pre-implant assessment of a maxillary left edentulous region. A cone-beam computed tomographic (CBCT) image was acquired and referred for consultation. Axial CBCT slices revealed a unilateral, well-defined, noncorticated, low-attenuation, transosseous defect posterior to the mastoid air cells in the right temporal bone. The borders of the osseous defect were smooth and continuous. No other radiographic signs suggestive of erosion or sclerosis were noted in the vicinity. The density within the defect was homogenous and consistent with a foramen and/or soft tissue. The patient's history and physical examination revealed no significant medical issues, and she was referred to a neuroradiologist for a second opinion. The diagnosis of an enlarged mastoid foramen was made and the patient was reassured.

• Korean Journal of Radiology
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• 제25권6호
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• pp.518-539
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• 2024

Coronary computed tomography angiography (CCTA) has emerged as a pivotal tool for diagnosing and risk-stratifying patients with suspected coronary artery disease (CAD). Recent advancements in image analysis and artificial intelligence (AI) techniques have enabled the comprehensive quantitative analysis of coronary atherosclerosis. Fully quantitative assessments of coronary stenosis and lumen attenuation have improved the accuracy of assessing stenosis severity and predicting hemodynamically significant lesions. In addition to stenosis evaluation, quantitative plaque analysis plays a crucial role in predicting and monitoring CAD progression. Studies have demonstrated that the quantitative assessment of plaque subtypes based on CT attenuation provides a nuanced understanding of plaque characteristics and their association with cardiovascular events. Quantitative analysis of serial CCTA scans offers a unique perspective on the impact of medical therapies on plaque modification. However, challenges such as time-intensive analyses and variability in software platforms still need to be addressed for broader clinical implementation. The paradigm of CCTA has shifted towards comprehensive quantitative plaque analysis facilitated by technological advancements. As these methods continue to evolve, their integration into routine clinical practice has the potential to enhance risk assessment and guide individualized patient management. This article reviews the evolving landscape of quantitative plaque analysis in CCTA and explores its applications and limitations.

• 한국정보처리학회논문지
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• 제5권12호
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• pp.3275-3284
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• 1998

본 논문에서는 각종 단층 촬영 의료영상 장비로 촬영한 2차원 단면화상 데이터들을 차원 재구성 알고리즘을 사용하여 3차원 영상으로 재구성한 다음, 웹 서버의 데이터베이스에 저장하고 관리하며, 인터넷 가상현실 표준언어인 VRML(Virtual Reality Modeling Language)로 표현된 3차원 의료영상을 비롯한 각종 의료영상 정보를 웹브라우저를 사용하여 검색해 볼 수 있는 의료영상정보시스템(Medical Image Information System)에 관하여 기술한다. 본 연구를 통하여 개발한 의료영상정보시스템에서는 단층 촬영된 2차원 단면화상을 처리한 다음, 3차원 의료 영상을 생성하기 위하여 표면기반 랜더링 방법(Surface-based Rendering Method)을 사용하였다. 인터넷을 통하여 전송되는 영상파일의 크기를 줄이기 위하여 삼각형 매쉬(Triangle Meshes)을 이루는 다각형의 개수를 줄이는 알고리즘을 사용하며, 3차원 의료영상 데이터의 크기를 약 50%이상 줄일 수 있다. 아울러, 3차원 영상 데이터 파일을 압축을 하게 되면 파일의 크기를 80%이상 줄일 수 가 있으므로 웹상에서 신속하게 3차원 의료영상 데이터를 검색할 수 있고, 의료영상을 VRML을 사용하여 표현하므로 고성능의 그래픽 카드가 없는 일반 PC에서도 인터넷을 통하여 디스플레이 할 수 있다. 또한, CGI(Common Gateway Interface)방식을 사용하여 서버의 데이터베이스에 저장되어 있는 CT(Computerized Tomography), MRI(Magnetic Resonance Imaging), PET(Positron Emission Tomography), SPECT(Single Photon Emission Computed Tomography)등의 단층 촬영 장비로 촬영한 다양한 종류의 디지털 의료영상을 사용자에게 의료영상정보시스템을 통하여 2차원 단면화상 또는 3차원 영상으로 표현하여 보여주고, 환자에 관한 각종 정보와 진단정보 등을 신속하게 제공한다. 본 논문에서 제안하는 의료영상정보시스템은 초고속 정보통신 망을 통하여 원격의료시스템을 구축하는데 활용될 수 있을 것이다.