• 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.

• 한국콘텐츠학회논문지
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• 제15권11호
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• pp.322-328
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• 2015

본 연구는 기존의 Mammogram와 Tomosynthesis를 비교하여 진단적 가치를 평가하고 피검자의 유선선량을 비교하여 Tomosynthesis의 활용에 대해서 고찰해 보고자 하였다. 2015년 1월 한 달 동안 본원을 내원한 환자 62명을 대상으로 선행 검사를 시행한 후 어떤 병변이 있을 때 추가적으로 Tomosynthesis를 시행하였는지 분석하였다. 유방촬영용 ACR phantom을 이용하였으며 자동 노출이 되도록 설정된 상태에서 촬영한 kVp와 mAs를 기준으로 하여 kVp는 고정하고 mAs를 단계적으로 변화를 주어 유선선량을 분석하였다. 그 결과 Tomosynthesis가 유방 병변 구별에 우수하였으며 2D Mammogram과 비교할 때 확연한 대조도 차이를 보였다. 또한 두 검사의 평균유선선량에서는 Mammogram(1.15 mGy)보다 Tomosynthesis(1.48 mGy)가 0.33 mGy정도 높았으나 추가검사의 불필요함으로 인해 장기적으로는 피폭선량이 감소하는 효과를 보였다. 그러므로 Tomosynthesis는 유방의 진단적 가치를 높임과 동시에 피폭선량을 줄일 수 있는 검사이며 향후 유방질환의 검사에 적합하게 적용되고 응용할 수 있을 것이다.

• 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.

• 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.

• Journal of the Korean Wood Science and Technology
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• 제50권4호
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• pp.246-255
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• 2022

The need for non-destructive testing and evaluation of Korean traditional wooden buildings is increasing because of their widespread deterioration. Among all types of deterioration, termite damage in wooden columns is the most difficult to detect with the naked eye because it starts inside the wood, and the initial deterioration is small. X-ray computed tomography (CT) is the best technology to investigate the inner state of wood that has less damage, but applying it to wooden columns between walls is challenging. Therefore, the feasibility of tomosynthesis, which is a method to reconstruct a coronal section of a subject with a few X-ray projections from a limited angle of rotation, was studied as an alternative to CT. Pine (P. densiflora) with three artificial holes was prepared as a specimen to evaluate the quality of reconstructed tomosynthesis images according to the different number of projections. The quality of the tomosynthesis images in the in-focus plane was evaluated using the contrast-to-noise ratios, while a vertical resolution between the images was assessed by determining the artificial spread function. The quality of the tomosynthesis image in the in-focus plane increased as the number of projections increased and then remained constant as the number of projections reached 21 or over. In the case of vertical resolution, there was no significant difference when 21 projections or more were used to reconstruct the images. A distinct difference between coronal section images was found when the distance was more than 10 mm from one plane to another plane.

• 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.

• 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.

• 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.

• 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.

• 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.