• 한국방사선학회논문지
• /
• 제16권5호
• /
• pp.585-594
• /
• 2022

현재 주로 사용되고 있는 디지털 방사선 검사용 검출기는 평면형의 구조를 가진 검출기로 이루어져 있어 곡률을 가진 검사 대상물의 디지털 방사선 검사 시 완전한 밀착이 불가능 하였다. 본 연구는 산업현장에서 배관 용접부를 대상으로 한 디지털 방사선 투과 검사 시 디지털 영상의 상질 개선을 위하여 곡률에 밀착이 가능한 커브드 형태의 검출기를 제작하였고, 공칭 두께가 각기 다른 6" 배관을 대상으로 평면형 검출기와 커브드 검출기를 사용한 디지털 방사선 영상을 획득하였다. 실험 결과, 평면형 검출기는 배관과 완전한 밀착이 되지 않아 배관 외곽부와 검출기 사이의 틈이 생기게 되고, 이로 인해 불선명도 차이가 생기면서 디지털 영상의 확산이 발생하는 것을 확인하였다. 반면, 커브드형 검출기는 배관 외곽부와 검출기 사이의 틈을 최소화 하여 평면형 검출기에 비해 디지털 영상의 확산이 적은 것을 확인하였다. 영상의 확신이 클수록 상질의 저하 및 판독의 오류가 발생할 수 있기 때문에 검사 대상물과 밀착이 가능한 검출기의 사용시 기존 평면형 검출기 보다 양질의 영상을 획득 가능할 것으로 사료된다.

• 대한디지털의료영상학회논문지
• /
• 제8권1호
• /
• pp.27-32
• /
• 2006

The rapid development in digital acquisition technology in radiography has not been accompanied by information regarding optimum radiolographic technique for use with an amorphus silicon flat panel detector. The purpose of our study was to compared imaging characteristics and image quality of an amorphus silicon flat panel detectors for digital chest radiography. All examinations were performed by using an amorphus silicon flat panel detector. Chest radiographs of an chest phantom were obtained with peak kilovoltage values of 60$\sim$150 kVp. Published data ell the effect of x-ray beam energy on imaging characteristics and image qualify when using an amorphus silicon flat panel detector. It is important that radiographers are aware of optimum kVp selection for an amorphus silicon flat panel detector system, particularly for the commonly performed chest examination.

• 대한안전경영과학회지
• /
• 제17권4호
• /
• pp.213-221
• /
• 2015

The aim of this study was to set up the optimal exposure condition according to detector type considering image quality (IQ) with radiation dose in chest digital radiography. We used three detector type such as flat-panel detector (FP) and computed radiography (CR), and charge-coupled device (CCD). Entrance surface dose (ESD) was measured at each exposure condition combined tube voltage with tube current using dosimeter, after attaching on human phantom, it was repeated 3 times. Phantom images were evaluated independently by three chest radiologists after blinding image informations. Standard exposure condition using each institution was 117 kVp-AEC at FP and 117 kVp-8 mAs at CR, and 117 kVp-8 mAs at CCD. Statistical analysis was performed by One way ANOVA (Dunnett T3 test) using SPSS ver. 19.0. In FP, IQ scores were not significant difference between 102 kVp-4 mAs and 117 kVp-AEC (28.4 vs. 31.1, p=1.000), even though ESD was decreased up to 50% ($62.3{\mu}Gy$ vs. $125.1{\mu}Gy$). In CR, ESD was greatly decreased from 117 kVp-8 mAs to 90 kVp-8 mAs without significant difference of IQ score (p=1.000, 24.6 vs. 19.5). In CCD, IQ score of 117 kVp-8 mAs was similar with 109 kVp-8 mAs (29.6 vs. 29.0), with decreasing from $320.8{\mu}Gy$ to $284.7{\mu}Gy$ (about 11%). We conclude that optimal x-ray exposure condition for chest digital radiography is 102 kVp-4 mAs in FP and 90 kVp-8 mAs in CR, and 109 kVp-8 mAs in CCD.

• 전자공학회논문지
• /
• 제53권12호
• /
• pp.120-127
• /
• 2016

디지털 x선 영상을 획득하기 위하여 최근에는 DR(digital radiography) 기술에 근거한 방사선 디텍터의 개발이 활발하게 진행되고 있다. 이러한 방사성 디텍터의 잡음 특성은, 균일한 노출에서 획득한 영상을 사용하여 NNPS(normalized noise power spectrum)를 측정하여 관찰한다. 이때 고정형태잡음(fixed pattern noise)을 제거하기위하여 두 장의 영상 차를 사용한다. 본 논문에서는 보다 정확한 NNPS를 측정하기 위하여, 먼저 여러 장의 영상을 획득하여 두 장의 평균영상을 구하고 그의 차를 사용하여 NNPS를 구하는 방법을 제안하였다. 이때 여러 장의 영상들의 평균으로 인하여 NNPS 값이 실제 값보다 작아지는데, 이러한 NNPS의 보정을 위하여, 평균할 때 사용한 영상 개수의 함수인 보정 상수도 함께 제안하였다. 또한 평균영상의 비를 사용하여 NNPS를 구하는 방법도 제안하였다. 실제 방사선 디텍터에서 획득한 영상을 사용하여 NNPS를 측정하는 실험을 통하여, 제안한 방법으로 NNPS 보다 정확하게 구할 수 있음을 관찰하였다.

• 대한의용생체공학회:의공학회지
• /
• 제12권1호
• /
• pp.35-42
• /
• 1991

In this paper, the information capacity, the intergrate performance measure of digital radiography system has been quantitatively analyzed. The effect of various factors affecting the information capacity of the digital radiography system in multistage detection processes has been considered and analyzed In detail. The results show that the more information capacity can be obtained with the smaller detector cell area, despite of the reduced signal to noise ratio due to the reduced number of X ray photons per detector cell. Considering the limit of human visual acuity, however. the sufficient resolution will be obtained when the detector cell size in $0.2{\times}0.2\textrm{mm}^2$ with 8 bit quantizaion. And also the results indicates that the information capacity may be severely reduced by the mixture of electric noise in final read-out stage.

• 대한디지털의료영상학회논문지
• /
• 제9권2호
• /
• pp.23-30
• /
• 2007

This study attempts to propose an appropriate method of using digital medical imaging equipments, by studying the effects of automatic exposure control(AEC), grid ratio and the change of radiography distance on the patient dose and detertor acquisition dose during the procedure of acquiring image through a digital medical imaging detector. The change of dose following the change of grid ratio's exposure and radiography distance was measured, by using an abdominal phantom organized with tissue equivalent materials in an amorphous silicon thin film transistor detecter installed with AWC. The case to use grid ratio 12 : 1, focal distance 180cm to radiography distance 110cm in AEC, the patient dose increased rather when we used grid ration 10 : 1, focal distance 110cm. When AEC was not used,the dose necessary for image acquisition decreased as the grid ratio became higher and the distance became further. but detector acquisition dose was not reduced when in applied AEC. When purchasing digiral medical imaging equipments, optional items such as AEC and grid shall be accurately selected to satisfy the use of the equipments. Radiography error made by radiation technologist and unnenessary patient dose can be reduced by selecting equipments with a radiography distance marker equipment when it did not apply AEC. These equipments can also be helpful in maintaining high imaging quality, one of the merits of digital detectors.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
• /
• pp.388-391
• /
• 2003

The properties of these detectors can be controlled by electronics and exposure conditions. Flat-panel detectors for digital diagnostic imaging convert incident x-ray images to charge images. Flat panel detectors gain more interest real time medical x-ray imaging. Active area of flat panel detector is $14{\times}17$ inch. Detector is based on a $2560{\times}3072$ away of photoconductor and TFT pixels. X-ray conversion layer is deposited upper TFT array flat panel with a 500m by thermal deposition technology. Thickness uniformity of this layer is made of thickness control technology(5%) of thermal deposition system. Each $139m{\times}139m$ pixel is made of thin film transistor technology, a storage capacitor and charge collection electrode having geometrical fill factor of 86%. Using the separate driving system of two dimensional mosaic modules for large area, that is able to 4.2 second per frame. Imaging performance is suited for digital radiography imaging substitute by conventional radiography film system..

• 대한방사선기술학회지:방사선기술과학
• /
• 제28권4호
• /
• pp.273-277
• /
• 2005

디지털 의료 영상의 빠른 발전은 새로운 기술-비정질 평판형 측정기-에 대한 최적의 기술이 동행되지 못했다. 이번 실험으로 비정질 평판형 측정기를 사용한 흉부 방사선 영상의 대한 환자선량과 영상의 화질에 대하여 비교하였다. 모든 실험은 비정질 평판형 측정기를 사용하였다. 흉부 팬텀을 사용한 흉부 방사선영상은 관전압 $60{\sim}150\;kVp$에서 획득하였다. 이번 실험을 통하여 획득된 비정질 평판형 측정기를 사용한 X-선 에너지에 대한 영상의 질과 환자선량에 관련된 정보들을 보고한다. 이 정보는 비정질 평판형 측정기를 사용한 시스템에서 최적의 관전압의 선정에 효과적인 정보를 제공하며, 특히 일반적인 흉부 검사에 적용될 수 있을 것이다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
• /
• pp.817-820
• /
• 2002

Amorphous selenium based flat panel detectors convert incident x-ray to electric signal directly. Flat panel detectors gain more interest real time medical x-ray imaging. TFT array and electric readout circuits are used in this paper offered by LG.Philips.LCD. Detector is based on a $1536{\times}1280$ array of a-Si TFT pixels. X-ray conversion layer(a-Se) is deposited upper TFT array with a $400{\mu}m$ by thermal deposition technology. Thickness uniformity of this layer is made of thickness control system technology$({\leq}5%)$. Each $139{\mu}m{\times}139{\mu}m$ pixel is made of thin film transistor technology, a storage capacitor and collecting electrode having geometrical fill factor of 86%. This system show dynamic performance. Imaging performance is suited for digital radiography imaging substitute by conventional radiography film system.

• 동력기계공학회지
• /
• 제12권6호
• /
• pp.70-77
• /
• 2008

The purpose of this study is to compare the quality of digital radiography image with that of classical film images for welded structure in power plants. The CMOS(Complementary Metal Oxide Semiconductor) flat panel detecter and Agfa D5 film are used to image flaw specimens respectively. In the test, CMOS flat panel detector has been determined to have a better image than that of film image. In the IQI(Image Quality Indicator) transmission test, one or two more line can be seen in digital image than in film image. Digital Radiography Test enabled to successfully detect all defects on the weld specimens fabricated with real reheat stem pipe and boiler tube as well. In the specific comparison test, Digital radiography test detected micro flaws in the size of 0.5 mm in length by 0.5 mm in depth. However, film test has limited it to 1.0 mm in length by 1.0 mm in depth. As a result of this study, digital radiography technology is estimated well enough to perform the inspection in the industry with far more cost effective way, compared to the classical film test.