• Journal of the Korean Society of Radiology
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• v.14 no.1
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• pp.7-14
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• 2020

The purpose of this study is to assess the usefulness of IR to compensate for uncertainties in inserting high density artificial objects in radiation treatment planning in the 3D-CRT treatment technique. CT images of the subjects with phantom and titanium inserted were obtained from images without IR and images with IR, and the dose evaluation factors HI, MU and volume evaluation factors Volume and PCI were compared. The results of the stainless steel and titanium phantom experiments showed that the volume of high density artificial material was reduced by 4.850% and 11.456% respectively when applying IR. MU decreased 0.924% and 1.181%. HI was down 0.106% and 0.272%. PCI decreased 0.358% and 0.867%. When IR was applied to CT images of subjects with vertebroplasty, Femur alignment pin and wrist alignment pin, the volume of artifacts decreased by 47.76%, 23.841%, and 49.339%. MU also decreased 0.924%, 0.294% and 1.675%, while HI decreased 1.232%, 0.412% and 1.695%. PCI decreases 4.022%, 0.512%, and 13.472%. In conclusion, When IR was applied to 3D-CRT treatment plan, both dose and volume in phantom and subject case with high density artificial insert were reduced.

• Journal of the Korean Society of Radiology
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• v.8 no.6
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• pp.317-323
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• 2014

This study aims to suggest and test methods using an orally inserted guiding device in order to improve a motion artifact by involuntary oral motor such as removing one's dentures and swallowing saliva clinically structured cervical spine scan and to make the optimal image by minimizing motion artifact. A cervical spine test was conducted with 30 patients who wore dentures among those who had a cervical spinal disease from January 1, 2014 through June 30, 2014. As for testing methods, after removing denture, T1-TSE-Sagittal, T2-TSE-Sagittal, T1-TSE-Axial and T2-TSE-Axial were obtained in a normal position and a supine position; the orally inserted guiding device was inserted in patients' mouth; and then T1-TSE-Axial and T2-TSE-Axial were retested. As a result, in SNR, T1-TSE-Axial before inserting an orally inserted guiding device was $22.33{\pm}8.59$; T1-TSE-Axial after inserting the orally inserted guiding device was $25.21{\pm}7.93$; T2-TSE-Axial before inserting the orally inserted guiding device was $14.49{\pm}5.74$; and T2-TSE-Axial after inserting the orally inserted guiding device was $16.61{\pm}6.72$. In CNR, T1-TSE-Axial was measured at $0.23{\pm}0.01$ while T2-TSE-Axial at $0.21{\pm}0.01$. As a result of the qualitative analysis, T1-TSE-Axial before inserting the orally inserted guiding device was $3.49{\pm}0.11$; T1-TSE-Axial after inserting the orally inserted guiding device was $3.95{\pm}0.14$; T2-TSE-Axial before inserting the orally inserted guiding device was $3.25{\pm}0.18$; and T2-TSE-Axial after inserting the orally inserted guiding device was $3.68{\pm}0.09$. As a result of using an orally inserted guiding device, the resolution and contrast of the images improved as the patients' involuntary artifact decreased because of removing dentures and swallowing saliva, and it was found that the interpretation of the images and identification of the diseases improved.

• Journal of the Korean Orthopaedic Association
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• v.56 no.3
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• pp.200-207
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• 2021

Periprosthetic femoral fractures remain as one of the most challenging complications following total hip arthroplasty. A thorough clinical and radiographic evaluation, precise classification, and understanding of modern management principles are essential to obtain optimal results for these fractures. The Vancouver classification system is a simple, effective, and reproducible method for the planning treatments of these injuries. The fractures associated with a stable femoral stem can be treated effectively with osteosynthesis, but periprosthetic femoral fractures associated with a loose stem require revision arthroplasty. This paper describes the principle of the treatment of patients with periprosthetic femoral fractures and how to assess the stability of the femoral stem.

• Journal of Biomedical Engineering Research
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• v.25 no.6
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• pp.455-464
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• 2004

Total hip arthroplasty(THA) considerably depends on high-experienced doctors because of high difficulty of the operation. Selection of acetabular cup's and femoral implant's position is closely related with success or failure of THA. Nevertheless the selection has usually depended on doctor's eye measurement, which makes the position accuracy of artificial joint lower after THA, often resulting in revision of THA. The present study determined a method to select accurately the position of acetabular cup and femoral implant through surgical simulation with 3D characteristic geometrical information of patient's pelvis and femur. We examined the change of femoral anteversion angle and neck-shaft angle accompanied by the change of acetabular cup's position and the insertion position of femoral implant. As result of analyzing geometrical information through different surgical simulations, we found that it was possible to select the accurate position of acetabular cup and femoral implant. It is expected to help doctors get experienced in THA operation through repetitive surgical simulations using the method suggested in the study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1157-1158
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• 2012

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.7 no.1
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• pp.39-44
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• 2014

The patellar clunk syndrome is one of the patellofemoral complication, caused by formation of the fibrous nodule at the suprapatellar region after total knee arthroplasty. The symptom involves painful catching, crepitus and clunk during knee extension. It has been mainly but not exclusively associated with the posterior stabilized total knee system. The fibrous nodule is entrapped in the femoral intercondylar notch of the femoral component during flexion and as the knee is extended, it displaces back to the trochlear groove abruptly and the typical symptoms occur. The risk of developing this complication is primarily related to the design of the femoral component and higher incidence was noted with earlier designs of posterior stabilized knee prosthesis. Modifications have been made to the femoral component to optimize the kinematics of the patellofemoral joint and thereby reduced the incidence of patellar clunk syndrome but did not eliminate the problem completely. Clinical examination is the gold standard of diagnosis and imaging study has been used as a possible adjunct to diagnosis. Especially ultrasonography is an imaging modality, which can be easily performed to detect the fibrous nodule on the quadriceps tendon. We report a case of patellar clunk syndrome which was diagnosed with ultrasonography.

• The Academic Congress of Korean Shoulder and Elbow Society
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• 2008.03a
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• pp.51-51
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• 2008

• Journal of the Korean Society of Radiology
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• v.16 no.2
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• pp.131-139
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• 2022

The purpose of this study was to insert a pedicle screw into a pig thoracic vertebrae, a general CT scan(Non MAR), and a thoracic axial image obtained with the Metallic Artifact Reduction for Orthopedic Implants (O-MAR) to reduce artifacts. The image obtained by reconstructing the algorithm (Standard, Soft, Bone, Detail) was used using the image J program. Signal to noise ratio(SNR) and contrast to noise ratio(CNR) were compared and analyzed by obtaining measured values based on the given equation. And this study was to investigate tube voltage and algorithm suitable for CT scan for thoracic pedicle screw insertion. As a result, when non-MAR was used, the soft algorithm showed the highest SNR and CNR at 80, 100, 120, and 140 kVp, On the other hand, when MAR was used, the standard algorithm showed the highest at 80 kVp, and the standard and soft algorithms showed similar values at 100 kVp. At 120 kVp, the Soft and Standard algorithms showed similar values, and at 140 kVp, the Soft algorithm showed the highest SNR and CNR. Therefore, when comparing Non-MAR and MAR, even if MAR was used, SNR and CNR did not increase in all algorithms according to the change in tube voltage. In conclusion, it is judged that it is advantageous to use the Soft algorithm at 80, 100, 120, and 140 kVp in Non MAR, the Standard algorithm at 80 and 100 kVp in MAR, and the Soft algorithm at 120 and 140 kVp. This study is expected to serve as an opportunity to further improve the quality of images by using selective tube voltage and algorithms as basic data to help evaluate images of pedicle screw CT scans in the future.

• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.581-588
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• 2019

MRI is superior when contrasted to help the organization generate artifacts resolution, but also affect the diagnosis and create a image that can not be read. Metal is inserted into the tooth, it is necessary to often be inhibited in imaging by causing the geometric distortion due to the majority and if the difference between the magnetic susceptibility of a ferromagnetic material or paramagnetic reducing them. The purpose of this study is to conduct a metal artefact in accordance with the analysis using a diamagnetic material. The magnetic material include a wire for the orthodontic bracket and a stainless steel was used as a diamagnetic material was used copper, zinc, bismuth. Testing equipment is sequenced using 1.5T, 3T was used was measured using a SE, TSE, GE, EPI. A self-produced phantom material was used for agarose gel (10%) to a uniform signal artifacts causing materials are stainless steel were tested by placing in the center of the phantom and cover inspection of the positive cube diamagnetic material of 10mm each length.After a measurement artefact artifact zone settings area was calculated using the Wand tool After setting the Low Threshold value of 10 in the image obtained by subtracting images, including magnetic material from a pure tool phantom images using Image J. Metal artifacts occur in stainless steel metal artifact reduction was greatest in the image with the bismuth diamagnetic materials of copper and zinc is slightly reduced, but the difference in degree will not greater. The reason for this is thought to be due to hayeotgi offset most of the susceptibility in bismuth diamagnetic susceptibility of most small ferromagnetic. Most came with less artifacts in image of bismuth in both 1.5T and 3T. Sequence-specific artifact reduction was most reduced artifacts from the TSE 1.5T 3T was reduced in the most artifacts from SE. Signal-to-noise ratio was the lowest SNR is low, appears in the implant, the 1.5T was the Implant + Bi Cu and Zn showed similar results to each other. Therefore, the results of artifacts variation of diamagnetic material, magnetic susceptibility (${\chi}$) is the most this shows the reduced aspect lower than the implant artificial metal artifacts criteria in the video using low bismuth susceptibility to low material the more metal artifacts It was found that the decrease. Therefore, based on the study on the increase, the metal artifacts reduction for the whole, as well as dental prosthesis future orthodontic materials in a way that can even reduce the artifact does not appear which has been pointed out as a disadvantage of the solutions of conventional metal artifact It is considered to be material.

• Journal of IKEEE
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• v.22 no.3
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• pp.854-857
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• 2018

It becomes important to analyze the effects of electromagnetic wave on human body, as various wireless equipments are widely used in daily life. SAR (specific absorption rate) is a parameter of the effects of electromagnetic wave on human body. However, it considers only human tissues, and it is difficult to evaluate the effects of electromagnetic wave when metal artifacts are inserted such as dental implants. This paper introduces a method to simulate SAR, and gets its simulated results. Simulated SAR of human head model with dental implants in 30 GHz 5th generation mobile communications (5G) frequency band is $2.50{\times}10^{-3}W/kg$ in maximum and $8.58{\times}10^{-7}W/kg$ in average. These values are absolutely below 1.6 W/kg Korean domestic SAR limit.