• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.53-59
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• 1999

The aim of this study is to improve the accuracy of field placement and junction between adjacent fields and block shielding through the use of a computed tomography(CT) simulator and virtual simulation. The information was acquired by assessment of Alderson Rando phantom image using CT simulator (I.Q. Xtra - Picker), determination of each field by virtual fluoroscopy of voxel IQ workstation AcQsim and colored critical structures that were obtained by contouring in virtual simulation. And also using a coronal, sagittal and axial view can determine the field and adjacent field gap correctly without calculation during the procedure. With the treatment planning by using the Helax TMS 4.0, the dose in the junction among the adjacent fields and the spinal cord and cribriform plate of the critical structure was evaluated by the dose volume histogram. The pilot image of coronal and sagittal view took about 2minutes and 26minutes to get 100 images. Image translation to the virtual simulation workstation took about 6minutes. Contouring a critical structure such as cribriform plate, spinal cord using a virtual fluoroscopy were eligible to determine a correct field and shielding. The process took about 20 minutes. As the result of the Helax planning, the dose distribution in adjacent field junction was ideal, and the dose level shows almost 100 percentage in the dose volume histogram of the spinal cord and cribriform plate CT simulation can get a correct therapy area due to enhancement of critical structures such as spinal cord and cribriform plate. In addition, using a Spiral CT scanner can be saved a lot of time to plan a simulation therefore this function can reduce difficulties to keep the patient position without any movements to the patient, physician and radiotherapy technician.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.3
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• pp.385-390
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• 2003

Traumatic injuries in the young permanent dentition are common, but root fractures, defined as fractures involving dentin, cementum and pulp, are relatively uncommon. Appropriate management of root fracture involves repositioning the coronal portion of the tooth fragment and firm immobilization with a splint for 2 to 3 month. Root canal treatment should not be initiated until the sign of necrosis or resorption are apparent because in most cases, the apical fragments maintain their vitality. The following case report describes a patient with root fractures injured three times over the period of 7 years. The results, clinically and radiographically, were acceptable, but long term periodic evaluation is required.

• Journal of Periodontal and Implant Science
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• v.41 no.5
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• pp.253-258
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• 2011

Purpose: Immediate implantation presents challenges regarding site healing, osseointegration, and obtaining complete soft-tissue coverage of the extraction socket, especially in the posterior area. This last issue is addressed herein using the double-membrane (collagen membrane+high-density polytetrafluoroethylene [dPTFE] membrane) technique in two clinical cases of posterior immediate implant placement. Methods: An implant was placed immediately after atraumatically extracting the maxillary posterior tooth. The gap between the coronal portion of the fixture and the adjacent bony walls was filled with allograft material. In addition, a collagen membrane (lower) and dPTFE membrane (upper) were placed in a layer-by-layer manner to enable the closure of the extraction socket without a primary flap closure, thus facilitating the preservation of keratinized mucosa. The upper dPTFE membrane was left exposed for 4 weeks, after which the membrane was gently removed using forceps without flap elevation. Results: There was considerable plaque deposition on the outer surface of the dPTFE membrane but not on the inner surface. Moreover, scanning electron microscopy of the removed membrane revealed only a small amount of bacteria on the inner surface of the membrane. The peri-implant tissue was favorable both clinically and radiographically after a conventional dental-implant healing period. Conclusions: Secondary closure of the extraction socket and immediate guided bone regeneration using the double-membrane technique may produce a good clinical outcome after immediate placement of a dental implant in the posterior area.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.699-707
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• 2007

This study was carried out to investigate the reaction characteristics of corona/catalyst hybrid $DeNO_x$ process. The experiments were performed by using the multi-staged pin-to-hole type corona reactor which is enable to control the pin-to-hole gap and to insert the catalyst. Also, used for this study, were catalysts which commercially used Pt, Pd and $TiO_2$, and oxygen and hydrocarbon ($C_2H_4$) as reagents. In the syn-gas test, at high temperatures in the range of $100{\sim}200^{\circ}C$, the corona-only $DeNO_x$ process did not reduce the $NO_x$ concentration effectively. However in the presence of ethylene and oxygen as reagents, the $NO_x$ removal efficiency was better at these high temperatures than corona-only $DeNO_x$ process. In addition, coronal catalyst hybrid process with $TiO_2$ showed more efficiency of $NO_x$ removal than Pt and Pd catalyst, because the $TiO_2$ catalyst was more active than Pt and Pd catalyst to converse the $NO_2$ to $HNO_3$. Furthermore, at the condition of real diesel exhaust gas, the $DeNO_x$ efficiency of corona/catalyst hybrid process was not good at higher reaction temperature and plasma density.

• Journal of Periodontal and Implant Science
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• v.52 no.2
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• pp.170-180
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• 2022

Purpose: This study was conducted to assess the effect of hard and/or soft tissue grafting on immediate implants in a preclinical model. Methods: In 5 mongrel dogs, the distal roots of P2 and P3 were extracted from the maxilla (4 sites in each animal), and immediate implant placement was performed. Each site was randomly assigned to 1 of the following 4 groups: i) gap filling with guided bone regeneration (the GBR group), ii) subepithelial connective tissue grafting (the SCTG group), iii) GBR and SCTG (the GBR/SCTG group), and iv) no further treatment (control). Non-submerged healing was provided for 4 months. Histological and histomorphometric analyses were performed. Results: Peri-implant tissue height and thickness favored the SCTG group (height of periimplant mucosa: 1.14 mm; tissue thickness at the implant shoulder and ±1 mm from the shoulder: 1.14 mm, 0.78 mm, and 1.57 mm, respectively; median value) over the other groups. Bone grafting was not effective at the level of the implant shoulder and on the coronal level of the shoulder. In addition, simultaneous soft and hard tissue augmentation (the GBR/SCTG group) led to a less favorable tissue contour compared to GBR or SCTG alone (height of periimplant mucosa: 3.06 mm; thickness of peri-implant mucosa at the implant shoulder and ±1 mm from the shoulder: 0.72 mm, 0.3 mm, and 1.09 mm, respectively). Conclusion: SCTG tended to have positive effects on the thickness and height of the periimplant mucosa in immediate implant placement. However, simultaneous soft and hard tissue augmentation might not allow a satisfactory tissue contour in cases where the relationship between implant position and neighboring bone housing is unfavorable.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.351-361
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• 2012

The leading surgical method for correcting the misalignment of the varus and valgus in the knee joint is the high tibial osteotomy (HTO). In the opening wedge HTO (OWHTO), there is no concern about damaging the peroneal nerve on the lateral tibia of the proximal fibula. OWHTO has been the preferred choice, as the opening of the correction angle can be modulated during the operation. The correction of the varus and valgus on the coronal plane are performed adroitly. Nevertheless, there have been numerous reports of unintended changes in the medial tibial plateau and posterior slope angle (PSA). The authors have developed an HTO method using computer-assisted surgery with the aim of addressing the abovementioned problems from an engineer's perspective. CT images of the high tibia were reconstructed three-dimensionally, and a virtual osteotomy was performed on a computer. In addition, this study recommends a surgical method that does not cause changes in the PSA after OWHTO. The results of the study are expected to suggest a clear relationship between the anteromedial cortex oblique angle of each patient and the PSA, and an optimal PSA selection method for individuals.

• Investigative Magnetic Resonance Imaging
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• v.3 no.1
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• pp.66-72
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• 1999

Purpose : To evaluate the usefulness of Dual Echo in Steady State(DESS) image in the diagnosis of chondromalacia of the knee compared with turbo spin-echo MR images Materials and Methods : We included 26 patients with chondromalacia of the knee. MR imaging was obtained with a 1.5T imager. Sagittal and coronal double echo T2 weighted images(TR/TE 3000-4200/16-96msec, FOV $140-160{\times}140-160mm$, matrix size $180{\times}256$, slice thickness 4.0mm, interslice gap 0.5mm), and sagittal DESS image(TR/TE 25.4/9.0msec, flip angle $35-45^{\circ}$, FOV $150-160{\times}150-160mm,{\;}matrix{\;}size{\;}192{\times}256$, effective slice thickness 1.5mm) were obtained. Cartilage lesions were staged according to a modified scheme proposed by Outerbirdge: grade 0, normal; grade 1, softening or/and swelling; grade 2, mild surface fibrillation or/and less than 50% of cartilage thickness; grade 3, severe surface fibrillation or/and loss of more than 50% of cartilage thickness but without exposure of subchondral bone; and grade 4, complete loss of cartilage with subchondral bone exposure. Gradings were determined by two readers with consensus, and patellofemoral, medial and lateral tibiofemoral compartments were evaluated. Results : Arthroscopic findings revealed grade 1 in seven cases, grade 2 in 21 cases, grade 3 in six cases, and grade 4 in 18 cases. Sensitivity of turbo spin-echo MR image was as follows; 0%, 14%, 0%, 61% in each grade, and sensitivity of DESS image was as follows; 0%, 33%, 50%, 67%, in each grade(p=0.001). In the detection of chondromalacic lesions regardless of gradings, sensitivity, specificity and accuracy of conventional MR image were 59.6% 88.6% 78.8%, and of DESS image, 73.1% 88.4%, 82.2%(p=0.007). Conclusion : For chondromalacia of knee joints, DESS images showed higher sensitivity than turbo spin-echo MR images. Therefore, DESS images will be helpful for diagnosis of chondromalacia of knee joints.

• Journal of Magnetics
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• v.20 no.4
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• pp.381-386
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• 2015

The purpose of this study is to improve diagnostic efficiency of clinical study by setting up guidelines for more precise examination with a comparative analysis of signal intensity and image distortion depending on the location of X axial of object when performing magnetic resonance diffusion weighted imaging (MR DWI) examination. We arranged the self-produced phantom with a 45 mm of interval from the core of 44 regent bottles that have a 16 mm of external diameter and 55 mm of height, and were placed in 4 rows and 11 columns in an acrylic box. We also filled up water and margarine to portrait the fat. We used 3T Skyra and 18 Channel Body array coil. We also obtained the coronal image with the direction of RL (right to left) by using scan slice thinkness 3 mm, slice gap: 0mm, field of view (FOV): $450{\times}450mm^2$, repetition time (TR): 5000 ms, echo time (TE): 73/118 ms, Matrix: $126{\times}126$, slice number: 15, scan time: 9 min 45sec, number of excitations (NEX): 3, phase encoding as a diffusion-weighted imaging parameter. In order to scan, we set b-value to $0s/mm^2$, $400s/mm^2$, and $1,400s/mm^2$, and obtained T2 fat saturation image. Then we did a comparative analysis on the differences between image distortion and signal intensity depending on the location of X axial based on iso-center of patient's table. We used "Image J" as a comparative analysis programme, and used SPSS v18.0 as a statistic programme. There was not much difference between image distortion and signal intensity on fat and water from T2 fat saturation image. But, the average value depends on the location of X axial was statistically significant (p < 0.05). From DWI image, when b-value was 0 and 400, there was no significant difference up to $2^{nd}$ columns right to left from the core of patient's table, however, there was a decline in signal intensity and image distortion from the $3^{rd}$ columns and they started to decrease rapidly at the $4^{th}$ columns. When b-value was 1,400, there was not much difference between the $1^{st}$ row right to left from the core of patient's table, however, image distortion started to appear from the $2^{nd}$ columns with no change in signal intensity, the signal was getting decreased from the $3^{rd}$ columns, and both signal intensity and image distortion started to get decreased rapidly. At this moment, the reagent bottles from outside out of 11 reagent bottles were not verified from the image, and only 9 reagent bottles were verified. However, it was not possible to verify anything from the $5^{th}$ columns. But, the average value depends on the location of X axial was statistically significant. On T2 FS image, there was a significant decline in image distortion and signal intensity over 180mm from the core of patient's table. On diffusion-weighted image, there was a significant decline in image distortion and signal intensity over 90 mm, and they became unverifiable over 180 mm. Therefore, we should make an image that has a diagnostic value from examinations that are hard to locate patient's position.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.166-179
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• 1999

Apical sealing is essential for the success of surgical endodontic treatment. Root-end cavity is apt to be contaminated with moisture or blood, and is not always easy to be dried completely. The purpose of this study was to evaluate the influence of dry methods of retrocavity on the apical seal in endodontic surgery. Apical seal was investigated through the evaluation of apical leakage and adaptation of filling material over the cavity wall. To investigate the influence of various dry methods on the apical leakage, 125 palatal roots of extracted human maxillary molar teeth were used. The clinical crown of each tooth was removed at 10 mm from the root apex using a slow-speed diamond saw and water spray. Root canals of the all the specimens were prepared with step-back technique and filled with gutta-percha by lateral condensation method. After removing of the coronal 2 mm of filling material, the access cavities were closed with Cavit$^{(R)}$. Two coats of nail polish were applied to the external surface of each root. Apical three millimeters of each root was resected perpendicular to the long axis of the root with a diamond saw. Class I retrograde cavities were prepared with ultrasonic instruments. Retrocavities were washed with physiologic saline solution and dried with various methods or contaminated with human blood. Retrocavities were filled either with IRM, Super EBA or composite resin. All the specimens were immersed in 2% methylene blue solution for 7 days in an incubator at $37^{\circ}C$. The teeth were dissolved in 14 ml of 35% nitric acid solution and the dye present within the root canal system was returned to solution. The leakage of dye was quantitatively measured via spectrophotometric method. The obtained data were analysed statistically using one-way ANOVA and Duncan's Multiple Range Test. To evaluate the influence of various dry methods on the adaptation of filling material over the cavity wall, 12 palatal roots of extracted human maxillary molar teeth were used. After all the roots were prepared and filled, and retrograde cavities were made and filled as above, roots were sectioned longitudinally. Filling-dentin interface of cut surfaces were examined by scanning electron microscope. The results were as follows: 1. Cavities dried with paper point or compressed air showed less leakage than those dried with cotton pellet in Super EBA filled cavity (p<0.05). However, there was no difference between paper point- and compressed air-dried cavities. 2. When cavities were dried with compressed air, dentin-bonded composite resin-filled cavities showed less apical leakage than IRM- or Super EBA-filled ones (p<0.05). 3. Regardless of the filling material, cavities contaminated with human blood showed significantly more apical leakage than those dried with compressed air after saline irrigation (p<0.05). 4. Outer half of the cavity showed larger dentin-filling interface gap than inner half did when cavities were filled with IRM or Super EBA. 5. In all the filling material groups, cavities contaminated with blood or dried with cotton pellets only showed larger defects at the base of the cavity than ones dried with paper points or compressed air.