[en] To compare the visibility of the mandibular canal at the different radiographic methods such as conventional panoramic radiographs, Vimplant multiplanar reformatting (MPR)-CT panoramic images, Vimplant MPR-CT paraxial images and film-based DentaScan MPR-CT images. Data of 11 mandibular dental implant patients, who had been planned treatment utilizing both panoramic and MPR-CT examination with DentaScan software (GE Medical systems, Milwaukee, USA), were used in this study. The archived axial CT data stored on CD-R discs were transferred to a personal computer with 17' LCD monitor. Paraxial and panoramic images were reconstructed using Vimplant software (CyberMed Inc., Seoul, Korea). Conventional panoramic radiographs, monitor-based Vimplant MPR-CT panoramic images, monitor-based Vimplant MPR-CT paraxial images, and film-based DentaScan MPR-CT images were evaluated for visibility of the mandibular canal at the mental foramen, 1 cm, 2 cm, and 3 cm posterior to mental foramen using the 4-point grading score. Vimplant MPR-CT panoramic, paraxial, and DentaScan MPR-CT images revealed significantly clearer images than conventional panoramic radiographs. Particularly at the region 1 cm posterior to mental foramen, conventional panoramic radiographs showed a markedly lower percentage of 'excellent' mandibular canal images than images produced by other modalities. Vimplant MPR-CT and DentaScan MPR-CT images did not show significant difference in visibility of the mandibular canal. The study results shoe that Vimplant and DentaScan MPR-CT imaging systems offer significantly better images of the mandibular canal than conventional panoramic radiograph.

[en] Hand-held dental x-ray system is a self contained x-ray machine designed to perform intraoral radiography with one or two hands. The issue about its usage as general dental radiography is still in dispute. The aim of the present study was to assess the relationship between the amount of battery charge and the tube voltage in different hand-held dental x-ray systems. Seven hand-held dental x-ray units were used for the study. Tube voltage was measured with Unfors ThinX RAD (Unfors Instruments AB, Billdal, Sweden) for 3 consecutive exposures at the different amount of battery charge of each unit. The average and the deviation percentage of measured kV from indicated kV of each unit were calculated. Tube voltage of only 1 unit was 70 kV (indicated by manufacturer) and those of the others were 60 kV. Tube voltage deviation percentage from the indicated kV at the fully charged battery was from 2.5% to -5.5% and from -0.8% to -10.0% at the lowest charged battery. Tube voltages of all units decreased as the residual amount of the battery charge decreased. It is suggested that the performance test for hand-held x-ray system should be performed for the minimum residual charged battery as well as the full charged one. Persistent battery charging is suggested to maintain the proper tube voltage of the hand-held portable x-ray system.

[en] To implement the database system of oral and maxillofacial radiological images using a commercial medical image management software with personally developed classification code. The image database was built using a slightly modified commercial medical image management software, Dr. Image v.2.1 (Bit Computer Co., Korea). The function of wild card '*' was added to the search function of this program. Diagnosis classification codes were written as the number at the first three digits, and radiographic technique classification codes as the alphabet right after the diagnosis code. 449 radiological films of 218 cases from January, 2000 to December, 2000, which had been specially stored for the demonstration and education at Dept. of OMF Radiology of Dankook University Dental Hospital, were scanned with each patient information. Cases could be efficiently accessed and analyzed by using the classification code. Search and statistics results were easily obtained according to sex, age, disease diagnosis and radiographic technique. Efficient image management was possible with this image database system. Application of this system to other departments or personal image management can be made possible by utilizing the appropriate classification code system.

[en] To compare the leakage and scattered radiation from hand-held dental X-ray unit with radiation from fixed dental X-ray unit. For evaluation we used one hand-held dental X-ray unit and Oramatic 558 (Trophy Radiologie, France), a fixed dental X-ray unit. Doses were measured with Unfors Multi-O-Meter 512L at the right and left hand levels of X-ray tube head part for the scattered and leakage radiation when human skull DXTTR ΙΙΙ was exposed to both dental X-ray units. And for the leakage radiation only, doses were measured at the immediately right, left, superior and posterior side of the tube head part when air was exposed. Exposure parameters of hand-held dental X-ray unit were 70 kVp, 3 mA , 0.1 second, and of fixed X-ray unit 70 kVp, 8 mA, 0.45 second. The mean dose at the hand level when human skull DXTTR ΙΙΙ was exposed with portable X-ray unit 6.39 μGy, and the mean dose with fixed X-ray unit 3.03 μGy (p<0.001). The mean dose at the immediate side of the tube head part when air was exposed with portable X-ray unit was 2.97 μGy and with fixed X-ray unit the mean dose was 0.68 μGy (p<0.01). The leakage and scattered radiation from hand-held dental radiography was greater than from fixed dental radiography

[en] To determine the proper image compression method and ratio without image quality degradation in intraoral digital radiographic images, comparing the discrete cosine transform (DCT)-based JPEG with the wavelet-based JPEG 2000 algorithm. Thirty extracted sound teeth and thirty extracted teeth with occlusal caries were used for this study. Twenty plaster blocks were made with three teeth each. They were radiographically exposed using CDR sensors (Schick Inc., Long Island, USA). Digital images were compressed to JPEG format, using Adobe Photoshop v. 7.0 and JPEG 2000 format using Jasper program with compression ratios of 5 : 1, 9 : 1, 14 : 1, 28 : 1 each. To evaluate the lesion detectability, receiver operating characteristic (ROC) analysis was performed by the three oral and maxillofacial radiologists. To evaluate the image quality, all the compressed images were assessed subjectively using 5 grades, in comparison to the original uncompressed images. Compressed images up to compression ratio of 14: 1 in JPEG and 28 : 1 in JPEG 2000 showed nearly the same the lesion detectability as the original images. In the subjective assessment of image quality, images up to compression ratio of 9 : 1 in JPEG and 14 : 1 in JPEG 2000 showed minute mean paired differences from the original images. The results showed that the clinically acceptable compression ratios were up to 9 : 1 for JPEG and 14 : 1 for JPEG 2000. The wavelet-based JPEG 2000 is a better compression method, comparing to DCT-based JPEG for intraoral digital radiographic images.

[en] Familial gigantiform cementoma is a rate fibro-cemento-osseous disease of the jaws which appears to be transmitted as an autosomal dominant trait with variable expressivity of the phenotype. A 7-year-old girl visited DKUDH complaining of the painless facial deformity. Clinically, significant facie-lingual expansion was observed at the left maxilla, left mandibular body and symphysis portion. Malposition of lower anterior teeth was found. Panoramic radiograph and CT scan showed the extensive expandile mixed lesion at maxilla and mandible. Bone scan revealed hot spot at the maxilla and left side of mandible. Histologic examination revealed moderately dense fibrous connective tissue with scattered masses resembling cementum. The patient's mother had a history of the mandibular resection due to benign tumor. Her younger brother had buccal expansion of right mandible. We report our finding of a family that has exhibited clinical, radiographic and histologic findings consistent with the familial gigantiform dementoma

[en] Sonography is an attractive supplement to mammography in breast cancer screening because it is relatively inexpensive, requires no contrast-medium injection, is well tolerated by patients, and is widely available for equipment as compared with MRI. Sonography has been especially valuable for women with mammographically dense breast because it has consistently been able to detect a substantial number of cancers at an early stage. Despite these findings, breast sonography has known limitations as a screening tool; operator-dependence, the shortage of skilled operators, the inability to detect microcalcifications, and substantially higher false-positive rates than mammography. Further study of screening sonography is still ongoing and is expected to help establish the role of screening sonography

[en] As the increased prevalence of breast cancer and the advances in breast evaluation awareness have resulted in an increased number of breast examinations and benign breast biopsies, several investigations have been performed to improve the diagnostic accuracy for breast lesions. Optical imaging of the breast that uses nearinfrared light to assess the optical properties of breast tissue is a novel non-invasive imaging technique to characterize breast lesions in clinical practice. This review provides a summary of the current state of optical breast imaging and it describes the basic concepts of optical imaging, the potential clinical applications for breast cancer imaging and its potential incorporation with other imaging modalities

[en] Cystic lymphangioma is an uncommon benign developmental tumor of the lymphatic system, seen rarely in adults. A 23-year-old man visited DKUDH complaining of the painless swelling in the right submandibular triangle area. It was reported that swelling had increased since 5 months ago. Clinically, fluctuant and mobile mass was palpated at the right submancivular area. CT scan showed a large, well-defined, homogenous low density mass, measuring 5.0X2.5X4.0 cm. T1W MRI scan demonstrated a large, multiseptated homogenous low signal mass with septum and rim enhancement. Proton-density and T2W MRI scan showed mass of high signal intensity. MRI scan was able to delineate better the enhanced multiseptation and extent of the lesion. Histopathologically, a lobulated cystic mass lined by a layer of flattened endothelium was observed

[en] This study was performed to demonstrate the method of image reformation of dental implants, using a personal computer with inexpensive software and to compare the images reformatted using the above method with those using Dentascan software. CT axial slices of 5 mandibles of 5 volunteers from GE Highspeed Advantage (GE Medical systems, U.S.A.) were used, Personal computer used for image reformation was PowerWave 604/120 (Power Computing Co, U.S.A.) and software used were Osiris (Univ. Hospital Of Geneva, Switzerland) and Import ACCESS V1.1(Designed Access Co., U.S.A.) for importing CT image and NIH Image 1.58 (NIH, U.S.A.) for image processing. Seven images were selected among the serial reconstructed cross-sectional images produced by Dentascan (DS group). Seven resliced cross-sectional images at the same position were obtained ned at the personal computer (PC group). Regression analysis of the measurements of PC group was done against those of DS group. Measurements of the bone height and width at the reformed cross-sectional images using Mac-compatible computer were highly correlated with those using workstation with Dentascan software (height : r2=0.999, p<0.001, width : p=0.991, p<0.001). So, it is considered that we can use a personal computer with inexpensive software for the dental implant planning, instead of the expensive software and workstation.