• Progress in Medical Physics
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• v.14 no.2
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• pp.131-140
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• 2003

As the importance of accuracy in measurings of 3-D anatomical structures continues to be stressed, an objective and quantitative of assessing image quality and accuracy of 3-D volume-rendered images is required. The purpose of this study was to evaluate the quantitative accuracy of 3-D rendered images obtained with MDCT, scanned at various scanning parameters (scan modes, slice thicknesses and reconstruction slice thickness). Twelve clinically significant points that play an important role for the craniofacial bone in plastic surgery and dentistry were marked on the surface of a dry human skull. The direct distances between the reference points were defined as gold standards to assess the measuring errors of 3-D images. Then, we scanned the specimen with acquisition parameters of 300 mA, In kVp, and 1.0 sec scan time in axial and helical scan modes (pitch 3:1 and 6:1) at 1,25 mm, 2.50 mm, 3.75 mm and 5.00 mm slice thicknesses. We performed 3-D visualizations and distance measurements with volumetric analysis software and statistically evaluated the quantitative accuracy of distance measurements. The accuracy of distance measurements on the 3-D images acquired with 1.25, 2.50, 3,75 and 5.00 mm slice thickness were 48%, 33%, 23%, 14%, respectively, and those of the reconstructed 1.25 mm were 53%, 41%, 43%, 36% respectively. Meanwhile, there were insignificant statistical differences (P-value<0.05) in the accuracy of the distance measurements of 3-D images reconstructed with 1.25 mm thickness. In conclusion, slice thickness, rather than scan mode, influenced the quantitative accuracy of distance measurements in 3-D rendered images with MDCT. The quantitative analysis of distance measurements may be a useful tool for evaluating the accuracy of 3-D rendered images used in diagnosis, surgical planning, and radiotherapeutic treatment.

• Journal of the Korean Orthopaedic Association
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• v.52 no.1
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• pp.40-48
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• 2017

Purpose: Soft tissue reconstruction of a defect around the foot and ankle is a particularly challenging procedure due to the anatomical and functional characteristics of this area. Hence, only a limited number of treatment options are available. Moreover, if patients wish to avoid additional scars on the ipsilateral lower leg for cosmetic reasons, even fewer options are available for treatment. The authors used an anterolateral thigh perforator flap for soft tissue defects in this area, when other surgical options were inadequate. The aim of this study was to report the clinical results and the efficacy of this procedure. Materials and Methods: Sixteen cases of soft tissue defects around the foot and ankle were included. Participants included 12 male and 4 female subjects, and the mean age was 34 years. The most common cause of defect was acute trauma, and the average follow-up period was 33 months. Flap survival time, surgical complications, and ambulation status at the final follow-up stage were evaluated. Results: All 16 flaps successfully survived, except for one case with partial flap necrosis that was thought to be due to weight bearing earlier than scheduled. All patients were able to walk independently without any aid at the final follow-up stage. No patients showed other significant surgical complications. Conclusion: The anterolateral thigh perforator flap is a good alternative for soft tissue defects of the foot and ankle, when other options are not applicable. This study also demonstrated that surgery using an anterolateral thigh perforator flap is safe and highly reliable.

• The Journal of the Korean bone and joint tumor society
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• v.10 no.1
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• pp.1-12
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• 2004

Purpose: The current study was performed to analyze the oncological and functional results, and the patient, the limb and the prosthesis survival of osteosarcoma around the knee in children according to the treatment options. Materials and Methods: From 1982 to 2002, 63 patients with osteosarcoma around the knee underwent surgical treatments before 16 years of age. Surgical treatment options were amputation, endoprosthetic replacement, and implantation of low heat-treated autogenous bone graft after wide resection of tumor. The mean age of patients was 11.5 years (4.4~16), and the mean follow-up period was 6.1 years (2.1~16.8). All patients had neoadjuvant and adjuvant chemotherapy. All endoprosthses were extendible types. Anatomical locations of osteosarcoma were distal femur in 40 patients, and proximal tibia in 23 patients. As regard to Enneking stage, 4 patients had stage $II_A$, 50 patients had stage $II_B$, and 9 patients had stage III tumors. Results: The 5 year survival rate of stage $II_B$ patients was 72.7% in amputation, 83.7% in endoprosthesis, and 100% in low heat-treated autogenous bone graft. The 5 year survival rate of salvaged limb was 84.4% in endoprosthesis, and 80% in low heat-treated autogenous bone graft. The survival rate of prosthesis was 92.7% at 5 years, 67.4% at 10 years in endoprosthesis, and 75% at 5 years in low heat-treated autogenous bone graft. Mean functional outcome scores were 8.7 points in amputation, 20.6 points in endoprosthesis, and 16 points in low heat-treated autogenous bone graft. Distant metastasis occurred 15.8% in amputation, 27% in endoprosthesis and local recurrence occurred 8.1% in endoprosthesis, 14.3% in low heat-treated autogenous bone graft. Major complications happened 26.3% in amputation, 35.1% in endoprosthesis, and 28.6% in low heat-treated autogenous bone graft. Conclusion: Limb salvage procedure had functionally better results than amputation in children with osteosarcoma around the knee. Reconstruction with endoprosthesis after resection of tumor had good results in children as adults. In certain circumstances as too small bone for endoprosthesis or minimal bony destruction or too skeletally immature patient, low heat-treated autogenous bone graft may be a good treatment option. Low heat-treated autogenous bone graft may be considered as not only a substitute for endoprosthesis but also a temporary method before endoprosthesis.

• Journal of Biomedical Engineering Research
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• v.25 no.4
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• pp.261-268
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• 2004

Osteoporosis is a clinical condition in which the amount of bone tissue is reduced and the likelihood of fracture is increased. It is known that the electrical property of the bone is related to its density, and, in particular, the electrical resistance of the bone decreases as the bone loss increases. This implies that the electrical property of bone may be an useful parameter to diagnose osteoporosis, provided that it can be readily measured. The study attempted to evaluate the electrical conductivity of bone using a technique of electrical impedance tomography (EIT). It nay not be easy in general to get an EIT for the bone due to the big difference (an order of 2) of electrical properties between the bone and the surrounding soft tissue. In the present study, we took an adaptive mesh regeneration technique originally developed for the detection of two phase boundaries and modified it to be able to reconstruct the electrical conductivity inside the boundary provided that the geometry of the boundary was given. Numerical simulation was carried out for a tibia phantom, circular cylindrical phantom (radius of 40 mm) inside of which there is an ellipsoidal homeogenous tibia bone (short and long radius are 17 mm and 15 mm, respectively) surrounded by the soft tissue. The bone was located in the 15 mm above from the center of the circular cross section of the phantom. The electrical conductivity of the soft tissue was set to be 4 mS/cm and varies from 0.01 to 1 ms/cm for the bone. The simulation considered measurement errors in order to look into its effects. The simulated results showed that, if the measurement error was maintained less than 5 %, the reconstructed electrical conductivity of the bone was within 10 % errors. The accuracy increased with the electrical conductivity of the bone, as expected. This indicates that the present technique provides more accurate information for osteoporotic bones. It should be noted that tile simulation is based on a simple two phase image for the bone and the surrounding soft tissue when its anatomical information is provided. Nevertheless, the study indicates the possibility that the EIT technique may be used as a new means to detect the bone loss leading to osteoporotic fractures.

• Radiation Oncology Journal
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• v.14 no.2
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• pp.149-158
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• 1996

Purpose : To get an accute steepness of dose gradients at outside the target volume in intracranial lesion and a less limitation of beam selection avoiding the high dose at normal brain tissue, this Photon Knife Radiosurgery System was developed in order to provide the three-dimensional dose distribution through the reconstruction of CT scan and the combined stereotactic trans-multiarc beam mode based on linear accelerator photon beam. Materials and methods : This stereotactic radiosurgery, Photon Knife based on linear accelerator photon beam was provided the non-coplanar multiarc and trans-multiarc irradiations. The stereotactic trans-multiarc beam mode can be obtained from the patient position in decubitus. This study has provided the 3-dimensional isodose curve and anatomical structures with the surface rendering technique. The dose distribution from the combined two trans-multiarcs (2M 2TM) was compared to that of four non-coplanar multiarcs (4M) with same collimator size of 25 mm in a diameter and total gantry movements. Results : In this study, it shows that the dose distributions of stereotactic beam mode are significantly depended on the selected couch and gantry angle in same collimator size. Practical dose distribution of combined stereotactic trans-multiarc beam has shown a more small rim thickness than that of the non-coplanar multiarc beam mode in axial, sagittal and coronal plane in our study. 3-Dimensional dose line displayed with surface rendering of irregular target shape is helpful to determine the target dose and to predict the prognosis in follow-up radiosurgery. Conclusions : 3-Dimensional dose line displayed with surface rendering of irregular target shape is essential in stereotactic radiosurgery. This combined stereotactic trans-multiarc beam has shown a less limitation of the selection couch and gantry beam angles for the target surrounding critical organs. It has shown that the dose distribution of combined trans-multiarc beam greatly depended on the couch and gantry angles. In our experiments, the absorbed dose has been decreased to $27%$ / mm in maximum at the interval of $50\%$ to $80\%$ of isodose line.

• Journal of Chest Surgery
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• v.36 no.4
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• pp.267-272
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• 2003

Background: Common treatment modalities for tracheal stenosis include conservative methods such as repeated balloon dilatation, removal of obstructive material through bronchoscopy and T-tube insertion as well as operative treatment methods. Recent advances in surgical approaches through tracheal resection and end-to-end anastomosis have been reported to give better functional and anatomical results. Material and Method: Between March 1990 and July 2002, 41 patients who received tracheal resection and end-to-end anastomosis at Asan Medical Center, University of Ulsan were studied retrospectively. Result: The causes for tracheal resection and end-to-end anastomosis included 26 cases of postintubation stenosis, 10 cases of primary tracheal tumors (3 benign, 7 malignant), 1 case of endobronchial tuberculosis, 2 cases of traumatic rupture, and 2 cases of tracheal invasion of a thyroid cancer, Of the 41 patients who received tracheal resection and reconstruction, 29 received tracheal resection and end-to-end anastomosis, and 12 received laryngotracheal anastomosis with cricoid or thyroid cartilage resection. Four of these patients received supralaryngeal release. The average length of the resected trachea was $3.6{\pm}1.0$cm. Of the 41 patients who received tracheal resection and end-to-end anastomosis, 30 (73.2%) experienced no postoperative complications, and 8 (19.5%) experienced granulation tissue growth and/or minor infections which improved after conservative management. Good or satisfactory results were therefore achieved in 92.7%. Complications included repeated granulation tissue growth in 7, wound infection in 2, anastomotic site dehiscence in 2, restenosis resulting in dyspnea on exertion in 1, and repeated postoperative aspiration requiring retracheostomy in 1. There was no early postoperative mortality. There were 3 cases of hospital death. Conclusion: In cases of proper length of tracheal lesion, excellent results were obtained after tracheal resection and end-to-end anastomosis. But, granulation tissue growth is so serious complication, it is necessary for continuous study and efforts to prevent it.