• Imaging Science in Dentistry
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• 제39권1호
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• pp.27-33
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• 2009

Purpose: The purpose of this study was to evaluate the clinical usefulness of the recently developed multi-detector computed tomography and cone beam computed tomography in pre-operative implant evaluation, by comparing them with the single detector computed tomography, already confirmed for accuracy in this area. Materials and Methods: Five partially edentulous dry human mandibles, with $1{\times}1mm$ gutta percha cones, placed in 5mm intervals posterior to the mental foramen on each side of the buccal part of the mandible, were used in this study. They were scanned as follows: 1) Single detector computed tomography: slice thickness 1mm, 200mA, 120kV 2) Multi-detector computed tomography: slice thickness 0.75mm, 250mA, 120kV 3) Cone beam computed tomography: 15mAs, 120kV Axial images acquired from three computed tomographies were transferred to personal computer, and then reformatted cross-sectional images were generated using V-Implant $2.0^{(R)}$ (CyberMed Inc., Seoul, Korea) software. Among the cross-sectional images of the gutta perch a cone, placed in the buccal body of the mandible, the most precise cross section was selected as the measuring point and the distance from the most superior border of the mandibular canal to the alveolar crest was measured and analyzed 10 times by a dentist. Results: There were no significant intraobserver differences in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). There were no significant differences among single detector computed tomography, multi-detector computed tomography and cone beam computed tomography in the distance from the most superior border of the mandibular canal to the alveolar crest (p>0.05). Conclusion: Multi-detector computed tomography and cone beam computed tomography are clinically useful in the evaluation of pre-operative site for mandibular dental implants, with consideration for radiation exposure dose and scanning time.

• 대한의용생체공학회:의공학회지
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• 제26권5호
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• pp.295-300
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• 2005

We introduce an x-ray micro tomography system capable of high resolution imaging of a local region inside a small animal. By combining two kinds of projection data, one from a full field-of-view (FOV) scan of the whole body and the other from a limited FOV scan of the region of interest, we have obtained zoomed-in images of the region of interest without any contrast a nomalies. We have integrated a micro tomography system using a micro-focus x-ray source, a $1248\times1248$ flat-panel x-ray detector, and a precision scan mechanism. Using the cross-sectional images taken with the zoom-in micro tomography system, we measured trabecular thicknesses of femur bones in postmortem rats. To compensate the limited spatial resolution in the zoom-in micro tomography images, we used the fuzzy distance transform for the calculation of the trabecular thickness. To validate the trabecular thickness measurement with the zoom-in micro tomography images, we compared the measurement results with the ones obtained from the conventional micro tomography images of the extracted bone samples.

• Imaging Science in Dentistry
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• 제41권3호
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• pp.101-106
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• 2011

Purpose : This study evaluated the potential use of the computed tomography indices (CTI) on cone beam CT (CBCT) images for an assessment of the bone mineral density (BMD) in postmenopausal osteoporotic women. Materials and Methods : Twenty-one postmenopausal osteoporotic women and 21 postmenopausal healthy women were enrolled as the subjects. The BMD of the lumbar vertebrae and femur were calculated by dual energy X-ray absorptiometry (DXA) using a DXA scanner. The CBCT images were obtained from the unilateral mental foramen region using a PSR-$9000N^{TM}$ Dental CT system. The axial, sagittal, and coronal images were reconstructed from the block images using $OnDemend3D^{TM}$. The new term "CTI" on CBCT images was proposed. The relationship between the CT measurements and BMDs were assessed and the intra-observer agreement was determined. Results : There were significant differences between the normal and osteoporotic groups in the computed tomography mandibular index superior (CTI(S)), computed tomography mandibular index inferior (CTI(I)), and computed tomography cortical index (CTCI). On the other hand, there was no difference between the groups in the computed tomography mental index (CTMI: inferior cortical width). Conclusion : CTI(S), CTI(I), and CTCI on the CBCT images can be used to assess the osteoporotic women.

• 대한의용생체공학회:의공학회지
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• 제29권1호
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• pp.46-51
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• 2008

We describe a backprojection filtering method for limited angle tomography. In order to reduce blur artifacts originated from the out-of-planes and control high-frequency noise, we employed two band-limited window functions, and which were realized by Hann filters in this study. Based on the experimentally measured data, the performance of the developed method is demonstrated by comparing with the conventional shift-and-add and filtered backprojection methods. Application of the developed method to the dental imaging has a potential to be used for the preoperative evaluation of the jaw for dental implants with much reduced patient dose instead of the conventional dental computed tomography.

• Journal of Yeungnam Medical Science
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• 제38권2호
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• pp.95-106
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• 2021

Infections involving the heart are becoming increasingly common, and a timely diagnosis of utmost importance, despite its challenges. F-18 fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is a recently introduced diagnostic tool in cardiology. This review focuses on the current evidence for the use of FDG PET/CT in the diagnosis of infective endocarditis, cardiac implantable device infection, left ventricular assist device infection, and secondary complications. The author discusses considerations when using FDG PET/CT in routine clinical practice, patient preparation for reducing physiologic myocardial uptake, acquisition of images, and interpretation of PET/CT findings. This review also functions to highlight the need for a standardized acquisition protocol.

• Journal of Korean Neurosurgical Society
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• 제64권2호
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• pp.247-254
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• 2021

Objective : The subaxial cervical pedicle screwing technique shows powerful biomechanical properties for posterior cervical fusion. When applying a pedicle screw using the freehand technique, it is essential to analyse cervical computed tomography and plan the surgery accordingly. Normal cervical computed tomography is usually performed in the supine position, whereas during surgery, the patient lies in a prone position. This fact leads us to suppose that radiological evaluations may yield misleading results. Our study aimed to investigate whether there is any superiority between preoperative preparation on computed tomography performed in the prone position and that performed in the supine position. Methods : This study included 17 patients (132 pedicle screws) who were recently operated on with cervical vertebral computed tomography in the prone position and 17 patients (136 pedicle screws) who were operated on by conventional cervical vertebral computed tomography as the control group. The patients in both groups were compared in terms of age, gender, pathological diagnosis, screw malposition and complications. A screw malposition evaluation was made according to the Gertzbein-Robbins scale. Results : No statistically significant difference was observed between the two groups regarding age, gender and pathological diagnosis. The screw malposition rate (from 11.1% to 6.9%, p<0.05), mean malposition distance (from 2.18 mm to 1.86 mm, p <0.05), and complications statistically significantly decreased in the prone position computed tomography group. Conclusion : Preoperative surgical planning by performing cervical vertebral computed tomography in the prone position reduces screw malposition and complications. Our surgical success increased with a simple modification that can be applied by all clinicians without creating additional radiation exposure or additional costs.

• 치과방사선
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• 제27권2호
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• pp.117-125
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• 1997

The purpose of this study was to evaluate the detectability of various radiographic techniques for mandibular condylar lesions. Erosive lesion, osteophyte and flattening were formed on the artificial mandibular condyle, and panoramic, transcranial, transorbital radiography, lateral and frontal tomography were taken. The results were as follows; 1. The detectability for erosive lesions was superior in the order of frontal tomography(96％), lateral tomography(78％), transorbital(59％), transcranial(16％) and panoramic(48％) radiography. 2. The location of erosive lesion that showed the highest detectability was the medial third in panoramic, the lateral third in transcranial, the central portion of anteroposterior direction in transorbital, the central portion of mediolateral direction and the posterior third in lateral tomography. Frontal tomography disclosed all erosive lesions except one anterolateral lesion. 3. The detectability of osteophyte was 100％ in lateral tomography, 78％ in transcranial and 56％ in panoramic radiography. 4. For flattening, lateral tomography showed the flattened condyle, but both panoramic and transcranial views showed only decreased bone density without the change of condylar shape.

• 구강회복응용과학지
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• 제32권1호
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• pp.87-92
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• 2016

이 임상증례의 목적은 상악 제2대구치의 해부학적 형태를 computed tomography (CT)를 이용해 확인하여 근관치료에 활용한 증례이다. 이번 증례에서는 두개의 구개치근을 갖는 상악 제 2대구치에서 성공적인 근관치료를 위해서 CT를 활용하여 해부학적 형태를 확인하여 활용하였다. Cone beam computed tomography (CBCT)의 사용은 구개치근과 협측치근이 겹쳐보이는 치근단 방사선 사진의 한계를 극복할 수 있게 한다.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제19권1호
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• pp.59-66
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• 2013

Purpose: Although Computerized Tomography is one of the most useful diagnosis devices and Frequency of use by all kind of patient is higher than other device, it can be hardly to find out adequate data to planning of Computerized Tomography Unit. So questions have been raised about how to organize the unit. Methods: In order to suggest architectural guideline of Computerized Tomography Unit, expert interview, field survey and analysis to the floor plan have been conducted in this article. The area calculation was based on center line. Results: This article suggests a number of the guideline and the example of the planning which contains how to design Computerized Tomography Unit. Especially, in the case of the example on the planning, main points of the guideline is reflected. Implications: The result of this survey would be useful as a reference when the architect tries to design Computerized Tomography unit.

• 터널과지하공간
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• 제18권4호
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• pp.263-271
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• 2008

3차원 탄성파 토모그래피 알고리즘으로서 Fast Marching Method와 프레넬 볼륨에 기반한 알고리즘의 현장 적용성을 검토하고자 댐 건설 예정부지에 3차원 토모그래피 탐사를 수행하였다. 재구성된 3차원 탄성파 속도 입방체는 실제 지층 구조와 매우 유사한 속도분포를 보였다. 또한 시추 시료의 RMR 자료와 탄성파 속도간 직접 상관관계 분석을 수행하여 얻어진 RMR 입방체는 미 시추 구간 대한 신뢰도 높은 암반분류 정보를 제공하는 것을 확인하였다. 3차원 탄성파 토모그래피의 현장 적용에 대한 충분한 가능성을 확인하였으며 향후 초동 주시 계산 및 역해 알고리즘의 개선으로 보다 경제적으로 향상된 탐사를 수행할 수 있을 것으로 기대한다.