• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제35권5호
• /
• pp.316-323
• /
• 2009

Purpose: This study was performed to evaluate three-dimensional positional change of the condyle using 3D CT after bilateral sagittal split ramus osteotomy (BSSRO) in skeletal class III patients. Patients and methods: Nine patients who underwent BSSRO for mandibular set-back in skeletal class III malocclusion without facial asymmetry were examined. Miniplates were used for the fixation after BSSRO. 3-D CT was taken before, immediately after, and 6 months after undergoing BSSRO. After creating 3D-CT images using V-works $4.0^{TM}$ program, axial plane, coronal plane, & sagittal plane were configured. Three dimensional positional change, from each plane to the condyle, of the nine patients was measured before, immediately after, and 6 months after undergoing BSSRO. Results: 1. The mean value of mandibular set-back for nine mandibular prognathism patients was 7.36 mm (${\pm}\;2.42\;mm$). 2. In the axial view, condyle is rotated inward immediately after BSSRO (p < 0.05), comparing with preoperative but outward 6 months after BSSRO comparing with postoperative (p < 0.05). 3. In the axial view, condyle is moved laterally immediately after BSSRO (p < 0.05), comparing with preoperative but regressed 6 months after BSSRO comparing with preoperative (p > 0.05). 4. In the frontal & coronal view, there is changed immediately after and 6 months after BSSRO, comparing with preoperative but no statistical difference. Conclusion: These results indicate that three-dimensional positional change of the condyle in skeletal class III patients is observed lateral displacement & inward rotation immediate after BSSRO, but the condyle in 6 months after BSSRO tends to regress to preoperative position.

• 소성∙가공
• /
• 제20권7호
• /
• pp.518-523
• /
• 2011

The three dimensional geometries of an aluminum open cell foam before and after uniaxial compressive loading were investigated using the X-ray micro CT(computed tomography). Aluminum 6101-T6 open cell foams of 10, 20, 40 ppi (pore per inch) were considered in this work. After the serial sectioning CT images of aluminum foams were obtained from non-destructive X-ray images, the exact 3D structure were reproduced and visualized with commercial image processing program. The relative density ratio was around the 7.0 to 9.0 range, the unit cells showed anisotropic shapes having the different dimensional ratios of 1.1 to 1.3 between the rise and the transverse directions. The yield stress increased with the relative density ratio and the volumetric strain increased proportionally with compressive strain. The plateau stress in the compressive stress-strain curve was caused by the buckling of ligaments.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1989년도 춘계학술대회
• /
• pp.39-43
• /
• 1989

In this paper, hierachical representation method with a 1-to-4 and 1-to-8 data structure is used to reconstruct the three-dimensional scene from two-dimensional cross sections provided by computed tomography with small memory computer system. To reduce the internal memory use, 2-D section is represented by quadtree, and 3-D scene is represented by octree. Octree is constructed by recursively merging consecutive quadtrees. This method uses 7/200 less memory than pointer type structure with all the case, and less memory up to 60.3% than linear octree with experimental data.

• Journal of International Society for Simulation Surgery
• /
• 제1권2호
• /
• pp.99-102
• /
• 2014

The skull defect can be made after the trauma, oncologic problems or neurosurgery. The skull reconstruction has been the challenging issue in craniofacial fields for a long time. So far the skull reconstruction with autogenous bone would be the standard. Although the autogenous bone would be the ideal one for skull reconstruction, donor site morbidity would be the inevitable problem in many cases. Meanwhile various types of allogenic and alloplastic materials have been also used. However, skull reconstruction with many alloplastic material have produced no less complications including infection, exposure, and delayed wound healing. Because the 3D printing technique evolved so fast that 3D printed titanium implant were possible recently. The aim of this trial is to try to restore the original skull anatomy as possible using the 3D printed titanium implant, based on the mirrored three dimensional CT images based on the computer simulation. Preoperative computed tomography (CT) data were processed for the patient and a rapid prototyping (RP) model was produced. At the same time, the uninjured side was mirrored and superimposed onto the traumatized side, to create a mirror-image of the RP model. And we fabricated Titanium implant to reconstruct three-dimensional orbital structure in advance, using the 3D printer. This prefabricated Titanium-implant was then inserted onto the defected skull and fixed. Three dimensional printing technique of titanium material based on the computer simulation turned out to be very successful in this patient. Individualized approach for each patient could be an ideal way to manage the traumatic patients in near future.

• Imaging Science in Dentistry
• /
• 제44권1호
• /
• pp.15-20
• /
• 2014

Purpose: This study aimed to assess the three-dimensional (3D) facial changes after orthognathic surgery by evaluating the spherical coordinates of facial lines using 3D computed tomography (CT). Materials and Methods: A 19-year-old girl was diagnosed with class III malocclusion and facial asymmetry. Orthognathic surgery was performed after orthodontic treatment. Facial CT scans were taken before and after orthognathic surgery. The patient had a menton deviation of 12.72 mm before surgery and 0.83 mm after surgery. The spherical coordinates of four bilateral facial lines (ramal height, ramal lateral, ramal posterior and mandibular body) were estimated from CT scans before and after surgery on the deviated and opposite side. Results: The spherical coordinates of all facial lines changed after orthognathic surgery. Moreover, the bilateral differences of all facial lines changed after surgery, and no bilateral differences were zero. Conclusion: The spherical coordinate system was useful to compare differences between the presurgical and postsurgical changes to facial lines.

• Journal of Trauma and Injury
• /
• 제22권2호
• /
• pp.206-211
• /
• 2009

Purpose: Abdominal CT (computed tomography) is a principal diagnostic imaging modality for torso trauma at the Emergency Department (ED). When acute osseous pelvic injuries are detected by abdominal CT, additional three-dimensional (3D) reconstruction pelvic CT is often performed. We compared abdominal CT with pelvic CT to provide information about acute osseous pelvic injuries. Methods: A retrospective investigation of patients'electronic medical records during the five year period between January 1, 2004 and December 31, 2008 among Korean soldiers who underwent pelvic CT after abdominal CT at the ED was conducted. Axial images of abdominal CT were compared with axial images and 3D reconstruction images of pelvic CT. Results: Sixteen patients underwent subsequent pelvic CT after abdominal CT. Axial images of abdominal CT showed the same results in terms of fracture detection and classification when compared to axial images and 3D reconstruction images of pelvic CT. Pelvic CT (including 3D reconstruction images) followed by abdominal CT neither detected additional fracture nor changed the fracture type. Conclusion: This study has failed to show any superiority of pelvic CT (including 3D reconstruction images) over abdominal CT in detecting acute osseous pelvic injury. When 3D information is deemed be mandatory, 3D reconstructions of abdominal CT can be requested rather than obtaining an additional pelvic CT for 3D reconstruction.

• Journal of International Society for Simulation Surgery
• /
• 제3권1호
• /
• pp.36-38
• /
• 2016

Fibrous dysplasia is a relatively rare disease but the management would be quite challenging. Because this is not a malignant tumor, the preservation of the facial contour and the various functions seems to be important in treatment planning. Until now the facial bone reconstruction with autogenous bone would be the standard. Although the autogenous bone would be the ideal one for facial bone reconstruction, donor site morbidity would be the inevitable problem in many cases. Meanwhile, various types of allogenic and alloplastic materials have been also used. However, facial bone reconstruction with many alloplastic material have produced no less complications including infection, exposure, and delayed wound healing. Because the 3D printing technique evolved so fast that 3D printed titanium implant were possible recently. The aim of this trial is to try to restore the original maxillary anatomy as possible using the 3D printing model, based on the mirrored three dimensional CT images based on the computer simulation. Preoperative computed tomography (CT) data were processed for the patient and a rapid prototyping (RP) model was produced. At the same time, the uninjured side was mirrored and superimposed onto the traumatized side, to create a mirror-image of the RP model. And we molded Titanium mesh to reconstruct three-dimensional maxillary structure during the operation. This prefabricated Titanium-mesh implant was then inserted onto the defected maxilla and fixed. Three dimensional printing technique of titanium material based on the computer simulation turned out to be successful in this patient. Individualized approach for each patient could be an ideal way to restore the facial bone.

• Imaging Science in Dentistry
• /
• 제33권3호
• /
• pp.151-159
• /
• 2003

Purpose: The purpose of this study is to evaluate the effectiveness and usefulness of newly developed personal computer-based software to eliminate the linear artifacts by the metal restorations. Materials and Methods: A 3D CT image was conventionally reconstructed using ADVANTAGE WINDOWS 2.0 3D Analysis software (GE Medical System, Milwaukee, USA) and eliminated the linear artifacts manually. Next, a 3D CT image was reconstructed using V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea) and the linear artifacts eliminated manually in the axial images by a skillful operator using a personal computer. A 3D CT image was reconstructed using V-works 4.0/sup TM/(Cybermed Inc., Seoul, Korea) and the linear artifacts were removed using a simplified algorithm program to eliminate the linear artifacts automatically in the axial images using a personal computer, abbreviating the manual editing procedure. Finally, the automatically edited reconstructed 3D images were compared to the manually edited images. Results and Conclusion: We effectively eliminated the linear artifacts automatically by this algorithm, not by the manual editing procedures, in some degree. But programs based on more complicated and accurate algorithms may lead to a nearly flawless elimination of these linear artifacts automatically.

• International Journal of CAD/CAM
• /
• 제9권1호
• /
• pp.121-128
• /
• 2010

The purpose of this study is to clarify the mechanical behavior of human lumbar vertebrae (L3/L4) with and without fusion bone under physiological axial compression. The author has developed the program code to build the patient specific three-dimensional geometric model from the computed tomography (CT) images. The developed three-dimensional model provides the necessary information to the physicians and surgeons to visually interact with the model and if needed, plan the way of surgery in advance. The processed data of the model is versatile and compatible with the commercial computer aided design (CAD), finite element analysis (FEA) software and rapid prototyping technology. The actual physical model is manufactured using rapid prototyping technique to confirm the executable competence of the processed data from the developed program code. The patient specific model of L3/L4 vertebrae is analyzed under compressive loading condition by the FEA approach. By varying the spacer position and fusion bone with and without pedicle instrumentation, simulations were carried out to find the increasing axial stiffness so as to ensure the success of fusion technique. The finding was helpful in positioning the fusion bone graft and to predict the mechanical stress and deformation of body organ indicating the critical section.

• 대한방사선기술학회지:방사선기술과학
• /
• 제45권2호
• /
• pp.127-134
• /
• 2022

In order to overcome the image quality limitations of the conventional C-arm, a flat panel detector (FPD) is used to enhance spatial resolution, detective quantum efficiency, frame rate, and dynamic range. Three-dimensional (3D) visualized information can be obtained from C-arm computed tomography (CT) equipped with an FPD, which can reduce patient discomfort and provide various medical information to health care providers by conducting procedures in the interventional procedure room without moving the patient to the CT scan room. Unlike a conventional C-arm device, a C-arm CT requires different basic safety and essential performance evaluation criteria; therefore, in this study, basic safety and essential performance evaluation criteria to protect patients, medical staff, and radiologists were derived based on International Electrotechnical Commission (IEC) standards, the Ministry of Food and Drug Safety (MFDS) standards in Korea, and the rules on the installation and operation of special medical equipment in Korea. As a result of the study, six basic safety evaluation criteria related to electrical and mechanical radiation safety (leakage current, collision protection, emergency stopping device, overheating, recovery management, and ingress of water or particulate matter into medical electrical (ME) equipment and ME systems: footswitches) and 14 essential performance evaluation criteria (accuracy of tube voltage, accuracy of tube current, accuracy of loading time, accuracy of current time product, reproducibility of radiation output, linearity and consistency in radiography, half layer value in X-ray equipment, focal size and collimator, relationship between X-ray field and image reception area, consistency of light irradiation versus X-ray irradiation, performance of the mechanical device, focal spot to skin distance accuracy, image quality evaluation, and technical characteristic of cone-beam computed tomography) were selected for a total of 20 criteria.