• 대한의용생체공학회:의공학회지
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• 제29권5호
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• pp.364-370
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• 2008

Recent development in large area flat-panel x-ray detector technology enables clinical application of digital tomosyntesis. Unlike conventional motion tomography using x-ray films, flat-panel x-ray detectors provide projection images in digital formats so that tomographic images can be synthesized in a more flexible way. For the digital tomosynthesis, precise movements of the x-ray source and the x-ray detector with respect to a fulcrum point are necessary. In this study, we apply the digital tomosynthesis technique to the flat-panel detector based micro-CT in which the flat-panel detector and the x-ray source rotate together on a circular arc. The experimental results suggest that flat-panel detector based 3D CTs can be used for digital tomosynthesis in the clinical environment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.572-576
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• 1997

X-ray laminography and DT(digital tomosynthesis) that can form a cross-sectional image of 3-D objects promise to be good solutions for inspecting interior defects of industrial products. The major factors of the digital tomosynthesis that influence on the quality of x-ray cross-sectional images are also discussed. The quality of images acquired from the DT system varies according to image synthesizing methods, the number of images used in image synthesizing, and X-ray projection angles. In this paper, a new image synthesizing method named 'log-root method' is proposed to get clear and accurate cross-sectional images, which can reduce both artifact and blurring generated by materials out of focal plane. To evaluate the quality of cross-sectional images, two evaluating criteria: (1) shape accuracy and (2) clearness in the cross-sectional image are defined. Based on this criteria, a series of simulations were performed, and the results show the superiority of the new synthesizing method over the existing ones such as averaging and minimum method.

• 전자공학회논문지
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• 제53권9호
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• pp.143-147
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• 2016

최근 디지털 단층영상합성 시스템 (digital tomosynthesis system, DTS)은 일반 X-ray의 영상 중첩현상과 전산화단층촬영장치 (computed tomography, CT)의 높은 선량의 문제점을 해결하기 위하여 개발되었다. 본 연구의 목적은 흉부 촬영용 디지털 단층영상합성 시스템 (chest digital tomosynthesis, CDT)의 재구성 알고리즘 개발 및 화질과 선량 평가를 수행하는 것이다. 영상의 재구성은 필터 후 역투영 (filtered back-projection, FBP)을 모델링하였고, 팬텀 영상을 획득하기 위한 X-선과 검출기 사이의 각도를 ${\pm}10^{\circ}$, ${\pm}15^{\circ}$, ${\pm}20^{\circ}$, 그리고 ${\pm}30^{\circ}$로 구성하였다. 영상의 화질 평가는 평균 제곱근 편차 (root mean square error, RMSE)와 신호대 잡음 변화율 (signal difference-to-noise ratio, SDNR)로 수행하였고, 선량 평가는 ${\pm}20^{\circ}$의 범위에서 유효선량으로 수행하였다. 결과적으로, 모든 각도에서 Slice thickness 필터를 적용한 팬텀영상이 가장 우수한 RMSE와 SDNR 결과를 나타내었고, 최종 유효 선량은 0.166 mSv로 측정되었다. 결론적으로, 개발한 CDT 재구성 알고리즘의 유용성을 증명하였고, 최종 유효 선량을 측정하여 CDT의 기초 실험 데이터를 구축할 수 있었다.

• 제어로봇시스템학회논문지
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• 제5권4호
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• pp.471-480
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• 1999

This paper presents design and performance improvement of a new digital tomosynthesis (DTS) system for object-detector synchronous rotation. Firstly, a new DTS system, called OSDR (Object-Detector Synchronous Rotation) is suggested and designed to acquire X-ray digital images. Secondly, the shape distortion of DTS images generated by an image intensifier is modeled. And a new synthesis algorithm, which overcomes the limitations of the existing synthesis algorithm, is suggested to improve the sharpness of the synthesized image. Also an artifact analysis of the DTS system is performed. Thirdly, some performance indices, which evaluate quantitatively performance improvement, are defined. And the experimental verification of the performance improvement is accomplished by the ODSR system newly designed. The advantages of the ODSR system are expressed quantitatively, compared with an existing system.

• 비파괴검사학회지
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• 제27권1호
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• pp.8-14
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• 2007

비파괴검사기법에 활용되고 있는 X-선 디지털 영상합성법(digital tomosynthesis)에서 단층영상의 선명도를 향상시킬 수 있는 방법을 개발하였다. 기존의 SAA (shift-and-add) 알고리즘은 blur artefact로 인하여 재구성된 단층영상이 매우 흐린 단점이 있다. 본 연구에서는 SAA에서 blur artefact가 발생되는 물리적 메커니즘에 착안하여, 최초 재구성된 단층영상에서 관심있는 단층의 데이터를 모두 0의 값으로 대체한 후 이를 다시 FP (forward projection) 및 BP (backprojection)를 수행하여 관심있는 단층에서의 blur artefact를 추출 보정하여 단층영상을 복원하고자 하였다. 개발한 알고리즘을 검증하기 위해 실제 실험 및 몬테칼로(Monte Carlo) 시뮬레이션을 통해 기존 SAA 방법과 비교하였으며, 단층영상의 선명도가 크게 향상됨을 확인하였다.

• 한국의학물리학회지:의학물리
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• 제32권2호
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• pp.50-58
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• 2021

Purpose: In this study, we investigated the relationship between the noise characteristics and the number of projected images in tomosynthesis using a digital phantom. Methods: The digital phantom consisted of a columnar phantom in the center of the image and a spherical phantom with a diameter of 80 pixels. A virtual scan was performed, and 128 projected images (Tomo_w/o) of the phantoms were obtained. The image noise according to the Poisson distribution was added to the projected images (Tomo_×1). Furthermore, another projected image with additional noise was prepared (Tomo_×1/2). For each dataset, we created datasets with 64 (half) and 32 (quarter) projections by removing the even-numbered images twice from the 128 (fully) projected images. Tomosynthesis images were reconstructed by filtered back projection (FBP). The modulation transfer function (MTF) was estimated using the sphere method, and the noise power spectrum (NPS) was estimated using the two-dimensional Fourier transform method. Results: The MTFs did not change between datasets, and the NPSs improved as the number of projected images increased. The noise characteristics of the Tomo_×1_half images were the same as those of the Tomo_×1/2_full. Conclusions: To achieve a reduction in the patient dose in tomosynthesis acquisition, we recommend reducing the number of projected images rather than reducing the dose per projection.

• Asian Pacific Journal of Cancer Prevention
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• 제17권7호
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• pp.3521-3526
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• 2016

Digital breast tomosynthesis (DBT) as a breast cancer screening modality, through generation of three-dimensional images during standard mammographic compression, can reduce interference from breast tissue overlap, increasing conspicuity of invasive cancers while concomitantly reducing false-positive results. We here conducted a systematic review on previous studies to synthesize the evidence of DBT efficacy, eventually 18 articles being included in the analysis. The most commonly emerging topics were advantages of DBT screening tool in terms of recall rates, cancer detection rates and cost-effectiveness, preventing unnecessary burdens on women and the healthcare system. Further research is needed to evaluate the potential impact of DBT on longer-term outcomes, such as interval cancer rates and mortality, to better understand the broader clinical and economic implications of its adoption.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.4109-4114
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• 2015

Background: Full-field digital mammography (FFDM) with dense breasts has a high rate of missed diagnosis, and digital breast tomosynthesis (DBT) could reduce organization overlapping and provide more reliable images for BI-RADS classification. This study aims to explore application of COMBO (FFDM+DBT) for effect and significance of BI-RADS classification of breast cancer. Materials and Methods: In this study, we selected 832 patients who had been treated from May 2013 to November 2013. Classify FFDM and COMBO examination according to BI-RADS separately and compare the differences for glands in the image of the same patient in judgment, mass characteristics display and indirect signs. Employ Paired Wilcoxon rank sum test was used in 79 breast cancer patients to find differences between two examine methods. Results: The results indicated that COMBO pattern is able to observe more details in distribution of glands when estimating content. Paired Wilcoxon rank sum test showed that overall classification level of COMBO is higher significantly compared to FFDM to BI-RADS diagnosis and classification of breast (P<0.05). The area under FFDM ROC curve is 0.805, while that is 0.941 in COMBO pattern. COMBO shows relation of mass with the surrounding tissues, the calcification in the mass, and multiple foci clearly in breast cancer tissues. The optimal sensitivity of cut-off value in COMBO pattern is 82.9%, which is higher than that in FFDM (60%). They share the same specificity which is both 93.2%. Conclusions: Digital Breast Tomosynthesis (DBT) could be used for the BI-RADS classification in breast cancer in clinical.

• 한국의학물리학회지:의학물리
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• 제21권4호
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• pp.360-366
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• 2010

최근 정밀한 암 치료를 위해 방사선 치료기술이 강도변도 방사선치료, 영상유도 방사선치료 등의 눈부신 발전을 이루어 왔다. 2000년 이후로는 치료실에서 환자의 실제 치료위치를 정확히 파악하여 정밀한 치료를 가능하게 하는 영상 유도방사선 치료기술이 사용되고 있으며 가장 중요한 기술 중 하나가 방사선 치료 전에 다양한 방법의 의료 영상을 이용하여 환자의 치료 위치를 보정하는 것으로 가장 최근의 기술로는 선형가속기에 장착된 2차원 평면검출기를 이용한 콘빔CT (Cone Beam CT: CBCT)가 사용되고 있다. 본 연구에서는 기존의 CBCT의 "half fan" 조건에서 획득된 projection영상을 이용하여 360도 회전한 모든 영상이 아닌 제한된 각도에서 획득한 투사영상을 이용하여 환자의 해부학적 정보를 볼 수 있는 디지털 영상합성영상(Digital Tomosynthesis) 기술을 구현하였고 실제 위치교정을 위해 촬영된 환자 데이터를 이용하여 방사선 치료 환자 위치 교정을 위한 효용성을 검증하였다. 그 결과 동일 단층상에서의 해부학적 정보 표현에서 CBCT 영상과 비교하였을 때 유사성을 보였고 선량적인 측면에서 우월성을 나타냈다. 이러한 DTS의 장점을 극대화 하고 최적화가 이루어진다면 방사선 치료 위치 보정용으로 CBCT를 대체 할 수 있는 기술이 될 수 있을 것이라 기대한다.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2015년도 춘계 종합학술대회 논문집
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• pp.151-152
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• 2015

유방 검사에서 Tomosynthesis는 Mammogram과 비교하여 유방 병변 구별에 우수하고 확연한 대조도 차이를 보이며 추가적인 유방촬영 검사나 재촬영을 감소시킴으로서 장기적으로 환자의 피폭선량이 감소하는 효과를 보이므로 유방 병변 진단의 효과를 높일 수 있는 유용한 검사이다.