• Imaging Science in Dentistry
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• 제30권1호
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• pp.16-22
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• 2000

Purpose : To evaluate the bone densities measured on copper-equivalent image of cross sectional view of mandibular edentulous premolar area obtained by multifuctional panoramic x-ray machine, PM 2002 CC with transversal slicing system. Materials and Methods: Panoramic cross sectional views with 8 mm focal layer of aluminum step and blocks, of hydroxyapatite (RA) step, 6 HA blocks and copper step wedge having 0.03 mm thickness of each step, and of 3 bone blocks cutted by 8 mm thickness mesiodistally and a dry mandible with copper step wedge were taken by using transversal slicing system in PM 2002 Cc. All reference-equivalent images were made and analyzed by NIH image program. Results: The average copper-equivalent value of cancellous bone of bone blocks on the panoramic cross sectional view was 0.026 ± 0.020 mm Cu. The calculated average bone density was 0.38g/cm². There was no significant difference (P>0.1) between the bone densities on intraoral digital view and on the panoramic digital cross sectional view. Conclusion: The copper-equivalent image of panoramic digital cross sectional view obtained by PM 2002 CC with very thin copper step wedge was supposed to be useful to measure the bone density of cancellous bone of mandible at the premolar edentulous area.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.117-120
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• 1996

In this paper, a new approach to acquire the cross-sentional image for automatic solder joint inspection of double-sided PCB using X-ray source is presented. We designed the apparatus with fixed X-ray source to realize the cross-sectional image by tunning object and detector synchronously. The cross-sectional images are captured at several view angle of X-ray source, the geometric image distortions caused by view angle and the shape of image intensifier are compensated. The precision variation of cross-sectional image by the change of view angle was investigated. Also we acquired the cross-sectional image to the solder joint of double-sided PCB and reconstructed the shape of solder joint.

• 치과방사선
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• 제28권1호
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• pp.111-126
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• 1998

In this study, radiographic evaluation was made using panoramic radiography and cross-sectional tomography of SCANORA/sup (R)/ in male and female adults in their 20's on the relationship between the maxillary sinus floor and the apex of the maxillary molar, to test the accuracy and effectiveness of the cross-sectional tomography, and to use this information in the assessment of preop. and postop. root canal treatment, apical surgery, extraction and implantology. Forty-one adults with an average age of 24.4 years were studied using panoramic radiography and cross-sectional tomography. In panoramic view and cross-sectional view, the position of the apices of maxillary molars were classified as separated, contacted, or protruded type; the general shape of the maxillary sinus floor was evaluated horizontally and vertically from cross-sectional tomography. The accuracy of each radiography was tested using maxilla from 5 fresh cadavers from the Anatomy Lab at Yonsei University Dental College, and panoramic view and cross-sectional tomography were taken in the same condition as with the patients. The results were as follows: 1. Panoramic view and cross-sectional view were taken in the maxilla specimen, and the actual distance between the maxillary sinus floor and the tooth apices were measured in the specimen; the median values of the distance from the tooth apices to the maxillary sinus floor in the panoramic view, cross-sectional view and in the actual maxilla specimen were 2.83 mm, 4.51mm, and 4.l5mm, respectively. In the cross-sectional view, the measured distance was close to the actual distance but in the panoramic view, the measured distance was far from the actual distance. 2. When the results of the panoramic view and cross-sectional view were compared, 40.5％ of the results agreed with each other in the two radiographic methods and buccal roots of the 2nd molar were the closest to the maxillary sinus floor in the cross-sectional tomography. 3. In cross-sectional view, when the vertical relationship of the maxillary sinus floor and maxillary roots was assessed, in 1st molars, type II (the sinus floor that extends down to the buccolingual furcation area) was predominant, while in 2nd molars, type I (the sinus floor located above the level connecting the buccal and lingual apices) was predominant. In the horizontal relationship, in 1st molars, type II (the lowest floor of the maxillary sinus located in between the buccal and lingual roots) was predominant; in 2nd molars, type I (the lowest floor of the maxillary sinus located on the buccal side of the buccal roots) and type II appeared in similar frequency. In conclusion, the SCANORA/sup (R)/ cross-sectional tomography was more effective than the frequently used panoramic view, in that the relationship of the maxillary molars and maxillary sinus floor can be evaluated more accurately and the buccolingual cross-sectional view can also be observed. And maxillary sinus floor that was close to maxillary 2nd molar had tendency to be located on buccal side than that close to 1st molar. Therefore, cross-sectional tomography is an effective and accurate method to evaluate the position of the teeth in relation to the sinus floor preoperative and can be easily used to diagnose localized periapical lesions. Also, the image quality obtained was quite satisfactory.

• 한국초등과학교육학회지:초등과학교육
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• 제38권1호
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• pp.116-129
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• 2019

This study investigated elementary students' spatial thinking and visualization when they learned the shape of volcanoes. For this purpose we used GeoMapApp to design instruction program and assessment items. In the instruction, students were asked to connect the floor plan view of Jeju island with the cross-sectional view of the same figure producted by GeoMapApp. Then they were asked to classify four sets of pictures of volcanoes based on the similarities of figures, that is, dome-shaped and shield volcanoes. In the assessment students solved three questions which examined how they connected the plan view and cross-sectional profile of Kilauea, draw cross-sectional profile of Mt. Fuji, and distinguished a shield volcano and dome-shaped one. Students' discourse data during the class were analyzed according to the amount to showing their spatial thinking and visualization. The instruction program using GeoMapApp assisted students to facilitate their spatial thinking for understanding of volcanoes. The outcomes of assessment showed even elementary students had good spatial thinking and visualization. Therefore, we argued spatial thinking and visualization for geoscientific understanding need to be included in the national science curriculum for elementary students.

• 치과방사선
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• 제24권2호
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• pp.361-368
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• 1994

Radiographic planning is needed for implant placement in order to determine implant length, jaw bone volume, anatomical stucture and so on. Radiographic examination includes conventional radiography, conventional tomography and CT scan. The most accurate mesurement can be obtained from CT scan. For the cross-sectional view of mandible, CT scan reconstruction is generally needed. But the cross-sectional view of mandible can be reformed by personal computer. This study was performed to examine the clinical usefulness of reformed image using personal computer in comparison with CT scan reconstructed image. CT axial slices of 4 mandibles of 4 volunteers were used. Digital imaging system was composed of Macintosh Ⅱ ci computer, high resolution Sony XC-77 CCD camera, Quick Capture frame grabber board and 'NIH Image' program. Seven reconstructed cross-sectional images within CT machine(CT group) were obtained. And seven reformed cross-sectional images(PC group) after digitization of CT axial slices into the personal computer were obtained. PC group was compared with CT group in the objective and subjective aspects. The results were as follow: 1. Measurement of mandibular height & width in both group showed insignificant difference(P>0.05). 2. Subjective assessment of the mandibular canal in both group showed insignificant difference(P>0.05). 3. Image reformation using personal computer could provide panoramic view, which could not be obtained in CT scan reconstruction.

• Imaging Science in Dentistry
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• 제32권3호
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• pp.153-157
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• 2002

Purpose : This study was performed to determine the proper reference line for taking axial computed tomograms from which the good cross-sectional views can be reformatted by multiplanar reconstruction. Methods : Three dry mandibles with implanted gutta percha cones in the extracted socket were scanned axially according to 6 reference lines of 2 mandibular positions with computed tomogram Hitachi W550. The accuracy of measurements of the lengths of implanted gutta perch a cones in the each cross-sectional view reformatted from axial computed tomogram by multiplanar reconstruction was evaluated. Results: The difference between the measurements and the real length of implant was smallest in the bucco-lingual views reformatted from the axial views scanned according to the reference line of group V-a. The smaller the angle difference between reference line and occlusal line was, the smaller the difference between the measurements in the bucco-lingual views reformatted from axial views and the real length of implant. The majority of measured widths of implants in the bucco-lingually reformatted views were larger than the actual values. Conclusions : When the mandible is inclined within the limitation of gantry angle and scanned with the reference line coincident with occlusal plane, the bucco-lingual view can be reformatted without deformation of images from the axially scanned images.

• Imaging Science in Dentistry
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• 제31권2호
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• pp.101-107
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• 2001

Purpose: To evaluate the precision of measurements of distances and angle in the cross-sectional views of linear tomogram of panorama and to assess the technique for visualizing the mandibular canal. Methods: Ten dry mandibles were radiographically examined with 3 continuous cross-sectional views of linear tomogram of panorama and 4 continuous computed tomograms. The distance between the superior border of canal and alveolar crest and the bucco-lingual width of alveolar bone at the level of the superior border of canal and the angle between the two lines above were measured. Measurements were performed by radiologist and implantologist group and compared with measurements on computed radiograms of the same areas. Results: The measurements differences for the distance of alveolar bone height between in panorama and in CT showed 0.9 mm±0.6 mm by radiologists and 1.3mm±0.8mm by implantologists. There was no statistically significant difference between two groups' measurements. The differences in measurements for the distance of alveolar bone width between in panorama and in CT showed 0.5mm±0.8mm by radiologists and 2.5mm±1.4 mm by implantologists. There was significant difference (P<0.05) between two groups' measurements. The average bucco-lingual inclination of alveolar bone above mandibular canal was average 95.8° in CT. The difference of measurements between two groups was average 1±0.9°. Three cross-sectional views of panorama could show that the mandibular canal crosses antero-lingually and slopes inferiorly from the posterior segment of the mandible. Conclusions: The measurements in the linear tomogram of panorama by radiologists gave the accurate values of the distances and the angle compared with the values in computed tomograms.

• Imaging Science in Dentistry
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• 제50권1호
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• pp.37-43
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• 2020

Purpose: The purpose of this study was to evaluate the accuracy of linear measurements in the horizontal and vertical dimensions based on object position and slice inclination in cone-beam computed tomography (CBCT) images. Materials and Methods: Ten dry sheep hemi-mandibles, each with 4 sites (incisor, canine, premolar, and molar), were evaluated when either centrally or peripherally positioned within the field of view (FOV) with the image slices subjected to either oblique or orthogonal inclinations. Four types of images were created of each region: central/cross-sectional, central/coronal, peripheral/cross-sectional, and peripheral/coronal. The horizontal and vertical dimensions were measured for each region of each image type. Direct measurements of each region were obtained using a digital caliper in both horizontal and vertical dimensions. CBCT and direct measurements were compared using the Bland-Altman plot method. P values <0.05 were considered to indicate statistical significance. Results: The buccolingual dimension of the incisor and premolar areas and the height of the incisor, canine, and molar areas showed statistically significant differences on the peripheral/coronal images compared to the direct measurements (P<0.05). Molar area height in the central/coronal slices also differed significantly from the direct measurements (P<0.05). Cross-sectional images of either the central or peripheral position had no marked difference from the gold-standard values, indicating sufficient accuracy. Conclusion: Peripheral object positioning within the FOV in combination with applying an orthogonal inclination to the slices resulted in significant inaccuracies in the horizontal and vertical measurements. The most undesirable effect was observed in the molar area and the vertical dimension.

• 대한전자공학회논문지
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• 제26권9호
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• pp.1317-1321
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• 1989

The nonuniqueness of solutions to inverse scattering problems for the reconstruction of cross sectional permitivity distributions on dielectric cylinder is illustrated in view of numerical analysis based on the spectral inverse scattering scheme with the moment-method procedures. It is also shown that some additional treatmenents such as multiple measurements, various incidences, etc. are not effective to assure the uniqueness.

• Journal of Periodontal and Implant Science
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• 제32권2호
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• pp.379-388
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• 2002

임플랜트의 성공을 위해서 정확한 방사선학적 검사는 가용골의 높이와 하악관의 위치를 평가하고 중요구조물의 손상을 방지하는데 있어 필수적이다. CT촬영법 중 영상재구성법을 이용한 방법(CT/MPR)은 하악관의 위치를 잘 보여준다. 치아에 평행한 협설 단면 (cross-sectional plane)을 얻기 위해서는 횡단면(axial plane)이 교합면과 평행하도록 해야 한다. 횡단면(axial plane)이 교합면과 평행하지 않으면 재구성된 협설 단면(cross-sectional plane)은 계획된 fixture의 방향과 각을 이루게 되어 그 fixture의 실제 dimension을 보여주지 못하게 된다. 협설단면(cross-sectional view)에서 측정한 가용골 높이가 실제 가용골 높이보다 너무 큰 경우, 수술시 하악관을 침범할 가능성이 있게 된다. 이 연구의 목적은 하악 임플랜트 CT 촬영시 횡단면이 임플란트를 위한 가용골 높이의 측정에 미치는 영향을 알아보는 것이다. 하악 대구치 부위의 임플랜트를 계획하고 radiographic stent를 만든 후 치과 방사사선과에서 하악 임플랜트 CT를 촬영한 40명의 환자, 45개 부위를 선택하였다. 임플랜트 CT의 central panoramic view에서 치조정과 하악관, stent를 tracing한 후, 치조정과 하악관간의 거리(available bone height, ABH)를 재구성된 협설단면상에서 측정하였다(uncorrected ABH). 다음으로, .stent 방향으로 그은 직선상에서 측정하였다(corrected ABH). 두 거리사이의 각을 측정하였다. 두 거리로부터 각각 fixture의 길이를 결정하였다. 연구 결과, 두 가용골의 높이간에는 제 1 대구치와 제 2 대구치에서 모두 유의성있는 차이를 보였다 (p<0.001). 차이가 1 mm 이상인 경우는 제 1 대구치에서 8.7%, 제 2 대구치에서 15.5% 였다. 차이가 2 mm 이상인 경우는 제 1 대구치에서 2.0%, 제 2 대구치에서 6.6%였다. 최대값은 제 1 대구치에서 2.5 mm, 제 2 대구치에서 2.2 mm 였다. 두 가용골의 높이차와 각과의 상관 관계는 제 1 대구치와 제 2 대구치에서 모두 양의 상관관계를 보였다. 상관 계수는 제 1 대구치에서 0.534, 제 2 대구치에서 0.728 였다. 제 2 대구치가 더 강한 양의 상관관계를 보였다. 두 가용골의 높이로부터 결정한 fixture의 길이가 일치하지 않는 경우는 제 1 대구치에서는 24.4%, 제 2 대구치에서는 28.9%였다.