• Nuclear Engineering and Technology
• /
• 제33권5호
• /
• pp.514-525
• /
• 2001

Optimum characteristics of digital X-ray sensor components were analyzed to develop intra- oral dental digital X-ray image sensor using indirect method. Parametric analysis was carried out to optimize the phosphor thickness and the fiber optic plate (FOP) coupling to charge coupled device (CCD). X-ray absorption and light diffusion in the phosphor layer were analyzed by the Monte Carlo method. Real time X-ray image was obtained with prototype X- ray image sensor using general CCD camera with 1∼10 Ip/mm resolution. It has been previously shown that large resolution degradation in X-ray images was caused by miss alignment of FOP to CCD and optical adhesive selection. In this study, we reported that X-ray image quality was greatly improved by using optimized characteristics of alignment device and phosphor thickness.

• 한국방사선학회논문지
• /
• 제15권2호
• /
• pp.153-158
• /
• 2021

치주질환의 조기 진단률 및 예측 정확도 향상을 위한 X-선 영상 분석은 매우 중요한 분야이다. 이러한 치과 X-선 영상의 화질 개선을 위한 인공 지능 기반의 알고리즘 개발 및 적용에 관한 연구는 전 세계적으로 널리 수행 중이다. 따라서 본 연구의 목표는 치주질환 예측을 위한 치과 X-선 영상에서의 초해상화 알고리즘의 모델링 및 적용 가능성에 관하여 평가하는 것이다. 초해상화 알고리즘은 convolution layer와 ReLU를 기반으로 구성하였고, 저해상도 영상을 2배로 업샘플링 한 영상을 입력으로 사용하였다. 딥러닝 훈련을 위해 사용한 치과 X-선 데이터는 1,500장을 사용하였다. 영상의 정량적 평가는 2가지 영상의 비교를 통해 유사도를 측정할 수 있는 인자인 root mean square error와 structural similarity를 사용하였다. 이와 더불어 최근에 개발된 no-reference 기반으로 사용되는 natural image quality evaluator 와 blind/referenceless image spatial quality evaluator를 추가적으로 분석하였다. 결과적으로 기존에 사용되던 bicubic 기반의 업샘플링 기법을 사용하였을 때에 비하여 제안하는 방법이 치과 X-선 영상에서 평균적으로 유사도와 no-reference 기반의 평가 인자가 각각 1.86 그리고 2.14배 향상됨을 확인하였다. 결론적으로 치주질환의 예측을 위한 초해상화 알고리즘의 치과 X-선 영상에서의 유용성을 증명하였고 향후 다양한 분야에서의 적용 가능성이 높을 것으로 기대된다.

• Nuclear Engineering and Technology
• /
• 제48권3호
• /
• pp.799-804
• /
• 2016

A miniature X-ray tube based on a carbon-nanotube electron emitter has been employed for the application to a dental radiography. The miniature X-ray tube has an outer diameter of 7 mm and a length of 47 mm. The miniature X-ray tube is operated in a negative high-voltage mode in which the X-ray target is electrically grounded. In addition, X-rays are generated only to the teeth directions using a collimator while X-rays generated to other directions are shielded. Hence, the X-ray tube can be safely inserted into a human mouth. Using the intra-oral X-ray tube, a dental radiography is demonstrated where the positions of an X-ray source and a sensor are reversed compared with a conventional dental radiography system. X-ray images of five neighboring teeth are obtained and, furthermore, both left and right molar images are achieved by a single X-ray shot of the miniature X-ray tube.

• 한국방사선학회논문지
• /
• 제6권6호
• /
• pp.465-471
• /
• 2012

본 연구에서는 ALOKA PDM-117(X-ray 측정용 선량계)선량계를 이용하여 구내방사선 촬영기에서 발생하는 방사선에 대하여 거리의 변화에 따른 선량분포를 3차원으로 측정하였다. 구내 방사선촬영에 있어서 XCP 필름 유지기구(XCP-DS FIT)를 사용하여 영상을 얻는 경우 방사선의 선량 분포는 변할 수 있고 이것은 방사선영상과 환자피폭에 영향을 미치게 된다. 따라서 위치에 따른 선량을 표준화하여 XCP 필름 유지기구 사용 유무에 따른 선량과의 관계를 알아볼 필요성이 있다. 본 연구에서는 측정된 3차원 선량분포를 통하여 등각촬영시 얻을 수 있는 최적의 영상과 동일한 선량을 얻기 위한 조사시간과 거리와의 관계 및 선량분포의 모서리 퍼짐 현상에 대한 결과를 정량적으로 측정하였다. 거리가 증가함에 따라 중심 선량은 감소하였지만 조사통 가장자리 부분의 방사선 퍼짐은 증가하는 경향을 보였다. 이것은 XCP 필름 유지기구를 사용하는 경우에 선속 가장자리 부분에서 방사선의 선량이 퍼지는 경향을 보이기 때문이므로 환자의 병소이외의 부분에 대한 피폭에 주의를 기울여야 함을 정량적으로 확인 하였다. 본 연구의 결과는 품질 좋은 치아영상을 얻고, 환자의 피폭선량을 줄이는데 매우 유용하게 사용되어 질 수 있을 것으로 사료된다.

• 한국방사선학회논문지
• /
• 제6권1호
• /
• pp.39-45
• /
• 2012

기존 구내 치근단 촬영용 장치는 환자 피폭선량, 촬영시 고통 등의 문제점을 지니고 있다. 본 연구에서는 이러한 문제점을 해결하기 위한 신개념의 삽입형 초소형 X선 시스템의 가능성을 검증하였다. 먼저 초소형 X선 튜브에 사용될 콜리메이터와 필터를 설계하기 위하여 Geant4를 이용하여 최적의 콜리메이터 두께와 필터 두께를 결정하였으며 CdTe 검출기와 PX4 모듈을 이용하여 결정된 두께에서의 X선 스펙트럼을 확인하였다. 또한 기존 상용화된 치근단 촬영장치와 XOFT사의 초소형 X선 튜브를 이용하여 제작된 치아 팬텀에 대한 영상을 획득하였다. 그 결과 제안된 신개념의 삽입형 초소형 X선 시스템은 기존 시스템과 유사한 영상의 질을 나타내었다. 이는 향후 치근단 촬영용 장치를 비롯하여 다양한 응용부위에 활용할 수 있음을 나타낸다.

• 치과방사선
• /
• 제29권2호
• /
• pp.387-396
• /
• 1999

In dentistry. RadioVisioGraphy was introduced as a first electronic dental x-ray imaging modality in 1989. Thereafter. many types of direct digital radiographic system have been produced in the last decade. They are based either on charge-coupled device(CCD) or on storage phosphor technology. In addition. new types of digital radiographic system using amorphous selenium. image intensifier etc. are under development. Advantages of digital radiographic system are elimination of chemical processing, reduction in radiation dose. image processing, computer storage. electronic transfer of images and so on. Image processing includes image enhancement. image reconstruction. digital subtraction, etc. Especially digital subtraction and reconstruction can be applied in many aspects of clinical practice and research. Electronic transfer of images enables filmless dental hospital and teleradiology/teledentistry system. Since the first image management and communications system(IMACS) for dentomaxillofacial radiology was reported in 1992. IMACS in dental hospital has been increasing. Meanwhile. researches about computer-assisted diagnosis, such as structural analysis of bone trabecular patterns of mandible. feature extraction, automated identification of normal landmarks on cephalometric radiograph and automated image analysis for caries or periodontitis. have been performed actively in the last decade. Further developments in digital radiographic imaging modalities. image transmission system. imaging processing and automated analysis software will change the traditional clinical dental practice in the 21st century.

• Imaging Science in Dentistry
• /
• 제42권4호
• /
• pp.237-242
• /
• 2012

Purpose: The objectives of this study were to survey the radiographic exposure parameters, to measure the patient doses for intraoral dental radiography nationwide, and thus to establish the diagnostic reference levels (DRLs) in intraoral dental X-ray examination in Korea. Materials and Methods: One hundred two intraoral dental radiographic machines from all regions of South Korea were selected for this study. Radiographic exposure parameters, size of hospital, type of image receptor system, installation duration of machine, and type of dental X-ray machine were documented. Patient entrance doses (PED) and dose-area products (DAP) were measured three times at the end of the exit cone of the X-ray unit with a DAP meter (DIAMENTOR M4-KDK, PTW, Freiburg, Germany) for adult mandibular molar intraoral dental radiography, and corrections were made for room temperature and pressure. Measured PED and DAP were averaged and compared according to the size of hospital, type of image receptor system, installation duration, and type of dental X-ray machine. Results: The mean exposure parameters were 62.6 kVp, 7.9 mA, and 0.5 second for adult mandibular molar intraoral dental radiography. The mean patient dose was 2.11 mGy (PED) and 59.4 $mGycm^2$ (DAP) and the third quartile one 3.07 mGy (PED) and 87.4 $mGycm^2$ (DAP). Doses at university dental hospitals were lower than those at dental clinics (p<0.05). Doses of digital radiography (DR) type were lower than those of film-based type (p<0.05). Conclusion: We recommend 3.1 mGy (PED), 87.4 $mGycm^2$ (DAP) as the DRLs in adult mandibular molar intraoral dental radiography in Korea.

• Imaging Science in Dentistry
• /
• 제47권4호
• /
• pp.247-254
• /
• 2017

Purpose: Dual-energy X-ray imaging is widely used today in various areas of medicine and in other applications. However, no similar technique exists for dental applications. In this study, we propose a dual-energy technique for dental diagnoses based on voltage-switching. Materials and Methods: The method presented in this study allowed different groups of materials to be classified based on atomic number, thereby enabling two-dimensional images to be colorized. Computer simulations showed the feasibility of this approach. Using a number of different samples with typical biologic and synthetic dental materials, the technique was applied to radiographs acquired with a commercially available dental X-ray unit. Results: This technique provided a novel visual representation of the intraoral environment in three colors, and is of diagnostic value when compared to state-of-the-art grayscale images, since the oral cavity often contains multiple permanent foreign materials. Conclusion: This work developed a technique for two-dimensional dual-energy imaging in the context of dental applications and showed its feasibility with a commercial dental X-ray unit in simulation and experimental studies.

• Restorative Dentistry and Endodontics
• /
• 제23권1호
• /
• pp.110-140
• /
• 1998

One of the problems facing in all modern dental hospitals is the much efforts, manpower and space are needed to effectively sort and stack patients' charts of the various dental departments. In addition, the storage and prompt arrangement of x-ray films is also a problem. Therefore, if dental charts as well as films could be computerized, it would be easier to store and keep them; by data basing, many space, manpower and cost would be saved: data could also be effectively managed for the purpose of academic researches. This would be an epoch -making event in the development of dental hospital management. The purpose of this study is to develop a dental information processing program, that will be used to store dental treatment records and digital image data using a new record media, the optical card. The patients' charts from the dental hospital were selected. The treatment records of the chart were put into the treatment data -recording area of the program, and the digital images of various dental x-ray films were made with a scanner. These data were stored in the optical card and analyzed to get the following results: 1. In this program it is possible to put treatment records and image data into and out from the optical card, and it is impossible to correct and delete all data recorded on the optical card. 2. All data in the optical card system can be searched and analyzed on database. 3. The resolution of image data stored in optical card is above 5.9 lp/mm. 4, All data of dental charts used as samples, stored to optical cards, occupies average 14%, In conclusion, with the development of the storage system using the optical card, a dental patient's life-time treatment record can be stored in one optical card and used as a substitute for the dental chart.

• 대한의용생체공학회:의공학회지
• /
• 제20권2호
• /
• pp.139-148
• /
• 1999

본 논문에서는 PC기반의 치과 수술 시스템을 설계하였다. 이 시스템은 수술 후의 3차원 영상을 예측할 수 있다. 따라서 환자는 수술 후에 CT를 다시 촬영하지 않아도 되며 방사선에 노출시킬 필용가 없다. 수술 전, 후의 두부(Cephalometry) X-ray 정보와 수술 전의 CT 데이터로부터 수술 후의 환자의 두개골을 예측한다. X-ray 필름과 수술 전의 CT를 해부학적 불변 계측점(anatomical landmarks) 방법을 기반으로 한 특이값 분해(SVD: singular value decomposition) 로 레지스트레이션(registration)을 하였으며, 이를 표면 재구성 영상화 시스템으로 설계하였다. 설계된 시스템의 유용성을 검증하기 위하여 건조 두개골 모델 실험과 실제 임상환자에 대한 임상실험을 시행하였으며 유의수준 0.05에서 유의차가 없는 것으로 나타났다.