• Imaging Science in Dentistry
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• 제38권4호
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• pp.209-213
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• 2008

Purpose : To evaluate the relative diagnostic accuracy of panoramic radiography and Water's projection in maxillary sinus inflammatory diseases by comparing the radiodensities of the images with those of CT. Materials and Methods : Panoramic radiographs, Waters' projection, and CT images from 55 subjects (11O sinuses) were included in this retrospective study. The radiodensity of each maxillary sinus in panoramic radiography was recorded separately as upper and lower divided horizontally by hard palate. In Waters' projection, the overall sinus radiodensity was recorded. The CT images were considered as gold standard. Results : In panoramic radiography, 83 sinuses had same upper and lower radiodensity and 72 of these were consistent with those of CT, 26 sinuses had different upper and lower radiodensity and 15 of these, upper radiodensity was consistent with CT, the remaining 11, lower radiodensity was consistent with CT. One sinus had upper radiolucency with lower radiopacity and both were consistent with those of CT. Altogether 73 (66.4%) among 110 sinuses in panoramic radiography showed full agreement with CT, 26 (23.6%) showed partial agreement with CT. 9 sinuses had no lower image under the hard palate in panoramic radiography due to the smaller size of sinus. In Waters' projection, the radiodensity of 105 sinuses (95.5%) were consistent with that of CT. Conclusion : The panoramic radiography showed 90.0% of the sinus conditions fully or partially which may appear less accurate than that of Water's view (95.5%) but with more detailed information of the inferior part of sinuses. (Korean J Oral Maxillofac Radiol 2008; 38 : 209-13)

• Journal of the Optical Society of Korea
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• 제14권3호
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• pp.245-259
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• 2010

We have developed mathematically precise image-processing algorithms for extracting panoramic images from fisheye images. Furthermore, we have successfully built a DSP-based panoramic camera employing single fisheye lens.

• Imaging Science in Dentistry
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• 제36권3호
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• pp.131-135
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• 2006

Purpose : To evaluate the true projection angles of film-side mandibular condyles in panoramic and transcranial radiographs. Materials and Methods : 52 panoramic and transcranial radiographs of 4 condyles from two human dry mandibles with gradual horizontal and vertical angle changes were taken. The results were compared with the standard panoramic and transcranial radiographs and the identical pairs were selected. Results and Conclusion : Panoramic radiography projected 10 degrees to the film-sided condyles both horizontally and vertically. Transcranial radiography projected 15 degrees to the film-sided condyles vertically. The medial and lateral poles were not forming the outline of condylar images in both projections when the horizontal angles of condyles were not sufficiently big enough.

• Journal of the Optical Society of Korea
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• 제10권2호
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• pp.67-75
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• 2006

A dedicated catadioptric panoramic lens with the rectilinear projection scheme is designed. The resolution is high enough to provide separate VGA quality images for the respective four directions and the image distortion is less than 0.5%.

• Imaging Science in Dentistry
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• 제34권2호
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• pp.63-67
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• 2004

Purpose: To make a focal trough (image layer) for an average maxillary dental arch of 6-year-old korean in panoramic radiography. Materials and Methods : Phantom for the maxillary dental arch was designed using intercanine width, intermolar width, tooth size, and interdental spacing to record the data of 6-year-old child. The characteristics of pre-corrected panoramic machine (for adult) was evaluated using the phantom, resolution test pattern for margin of the image layer, and metal ball for the center of the image layer. Panoramic image layer of the child was developed by means of decreasing the speed of film-cassette and positioning the phantom backwards, and then the characteristics of post-corrected panoramic machine (for child) were reevaluated. Results: At post-corrected panoramic image layer, beam projection angles at all interdental areas increased for about 2.6-3.8°, the position of the image layer was shifted toward the rotation center for about 2.5 mm at the deciduous central incisior area. The width of image layer decreased at all areas. Conclusion : Increased beam projection angle will reduce the disadvantage of tooth overlap, and the same form between the center of the image layer and dental arch will improve image resolution.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.355-356
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• 2007

This paper proposes a new panoramic image synthesis method using flash and no-flash image pairs, which reduces undesirable artifacts. Generally, in panoramic images, it is difficult to determine to use a flash in indoor environment. A flash image has unwanted artifacts such as hot spots and tunnel effect whereas a no-flash image also has artifacts like glass reflection. We derive cross projection tensors using flash and no-flash image pairs and transform the gradient field of a no-flash image using them. The image reconstructed from the modified gradient provides enhanced results, which are applied to synthesis of panoramic images. The proposed method can provide a better panoramic image than the conventional method. Experimental results show the effectiveness of the proposed method.

• 치과방사선
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• 제16권1호
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• pp.31-39
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• 1986

This study was performed to compare the difference of intraoral bisecting and panoramic techniques in evaluating the relationship of antral floor and maxillary roots. The vertical distances from maxillary root apices to antral floor were measured on both orthopantomograms and bisecting projections obtained from fifty subjects. The results were as follows, 1. Tooth lengths measured on orthopantomogram were larger than on bisecting projection and the magnification ratios were 1.08-1.17. 2. The dimensions from maxillary root apices to antral floor measured on orthopantomogram were larger than on bisecting projection. 3. The above results held true regardless of age and sex.

• Imaging Science in Dentistry
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• 제33권4호
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• pp.217-221
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• 2003

Purpose : To evaluate the use of the vertical tube shift from a panoramic film and a periapical film to localize unerupted maxillary incisors and supernumeraries. Materials and Methods : The total of 103 displaced maxillary incisors or embedded supernumeraries were examined in this study. The vertical tube shift technique with panoramic and periapical radiography by normal projection taken and compared to localize the position of the embedded maxillary incisors or supernumeraries by a radiologist and 5 general dentists. The gold standard used for the radiographic comparisons was the true position of the embedded tooth as confirmed by horizontal tube shift technique using three periapical radiographs. The general dentist examiners were instructed on the use of the modified acronym 'SLDOBU' by the radiologist as it pertains to panoramic radiographs as the principle of vertical tube shift. Results: All of the embedded maxillary incisors and supernumeraries were successfully located using the vertical tube shift from a panoramic and a maxillary anterior periapical radiograph by the radiologist and 5 general dentists. Conclusion: The use of a panoramic film with a periapical film combination for a vertical tube shift can be useful to localize unerupted maxillary incisors and supernumeraries.

• 한국광학회:학술대회논문집
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• 한국광학회 2004년도 하계학술발표회
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• pp.74-75
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• 2004

• 대한전자공학회논문지SP
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• 제45권6호
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• pp.108-116
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• 2008

본 논문은 시점이 변화하는 동적 비디오에서 파노라마 배경을 생성하고 객체 추적을 가능하게 하는 알고리듬을 제안한다. 보다 구체적으로, 카메라로 입력되는 인접한 두 영상에서 추출된 특징점으로 부터 영상간의 관계를 유도하며, 이를 이용한 실린더 투영, 영상의 재정렬, 그리고 겹침 지역의 일그러짐을 최소화 하기 위한 스티칭(stitching) 및 블렌딩(blending)을 수행한다. 이 과정에 의해서 생성 된 배경을 기준으로 현재 입력 영상과 차분을 계산하여 객체 추적을 수행했다. 제안된 방법은 배경생성이 완료된 이후부터는 객체의 감시만을 수행하므로 실시간으로 넓은 영역의 감시가 가능하며, 이를 통한 지속적인 객체의 추적이 가능하다. 따라서 향후 공공장소 등과 같이 넓은 영역에서의 감시, 추적에 이용할 수 있다.