• Imaging Science in Dentistry
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• v.44 no.1
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• pp.15-20
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• 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.

• Hip & pelvis
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• v.36 no.2
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• pp.87-100
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• 2024

Total hip arthroplasty (THA) is an effective treatment for osteoarthritis, and the popularity of the direct anterior approach has increased due to more rapid recovery and increased stability. Instability, commonly caused by component malposition, remains a significant concern. The dynamic relationship between the pelvis and lumbar spine, deemed spinopelvic motion, is considered an important factor in stability. Various parameters are used in evaluating spinopelvic motion. Understanding spinopelvic motion is critical, and executing a precise plan for positioning the implant can be difficult with manual instrumentation. Robotic and/or navigation systems have been developed in the effort to enhance THA outcomes and for implementing spinopelvic parameters. These systems can be classified into three categories: X-ray/fluoroscopy-based, imageless, and computed tomography (CT)-based. Each system has advantages and limitations. When using CT-based systems, preoperative CT scans are used to assist with preoperative planning and intraoperative execution, providing feedback on implant position and restoration of hip biomechanics within a functional safe zone developed according to each patient's specific spinopelvic parameters. Several studies have demonstrated the accuracy and reproducibility of robotic systems with regard to implant positioning and leg length discrepancy. Some studies have reported better radiographic and clinical outcomes with use of robotic-assisted THA. However, clinical outcomes comparable to those for manual THA have also been reported. Robotic systems offer advantages in terms of accuracy, precision, and potentially reduced rates of dislocation. Additional research, including conduct of randomized controlled trials, will be required in order to evaluate the long-term outcomes and cost-effectiveness of robotic-assisted THA.

• Tunnel and Underground Space
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• v.22 no.5
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• pp.339-345
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• 2012

Information on the deformation behavior and fracture strength of rocks subjected to dynamic loadings is important to stability analyses of underground openings underground vibration due to rock blasts, earthquakes and rock bursts. In this study, Split Hopkinson Pressure Bar (SHPB) system was applied to estimate dynamic compressive and tensile fracture strengths of limestone and also examine deformation behavior of limestones under dynamic loadings. A micro-focus X-ray CT scanner was used to observe non-destructively inside the impacted limestone specimens. From the dynamic tests, it was revealed that the limestone have over 140MPa dynamic compressive strength and the strain-rate dependency of the strength. Dynamic Brazilian tensile strength of the limestone exceeds 21MPa and shows over 3 times static Brazilian tensile strength.

• Journal of the Korean Society of Radiology
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• v.7 no.3
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• pp.175-179
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• 2013

To find out the appropriate defensive measures for protectors and radiation workers in rotating radiation generating devices such as CBCT and panorama, irradiation dose depending on the position was compared and analyzed. The devices such as panorama DP-90-P PAX-500 (Vatech, Korea) and CBCT DCT-90-P IMPLAGRAPHY Dental CT system (Vatech, Korea) were used. As irradiation dose measuring instruments, Ion chamber model 2026 and Reader 20X5-60E were used. The exposure conditions were set as the factor used in the clinical trial. The result of the experiment showed that panorama was the highest, 81${\mu}R$, at point A where the test starts first and the lowest, 53${\mu}R$, at point D where the test ends. In case of CBCT, it was the highest, 1,021${\mu}R$, at point D where the test ends and was measured as the highest, 809.67${\mu}R$, at point A where the test starts. If protectors and radiation workers are forced to examine a patient holding him, they should be positioned in the middle of the point where X ray tube starts to rotate and the point where it ends to avoid the position where radiation dose is the most. And due to the nature of equipment, it will be the safest for them to stand at the opposite side of the machine and to uphold it from the rear rather than upholding it from the side of a patient and they should wear appropriate the protection gear.

• The Journal of Korean Society for Radiation Therapy
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• v.28 no.2
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• pp.123-130
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• 2016

Purpose : The aim of this study was to compare the differences between the volumes acquired with four-dimensional computed tomography (4DCT)images with a reconstruction image-filtering algorithm and cone-beam computed tomography (CBCT) images with dynamic phantom. Materials and Methods : The 4DCT images were obtained from the computerized imaging reference systems (CIRS) phantom using a computed tomography (CT) simulator. We analyzed the volumes for maximum intensity projection (MIP), minimum intensity projection (MinIP) and average intensity projection (AVG) of the images obtained with the 4DCT scanner against those acquired from CBCT images with CT ranger tools. Results : Difference in volume for node of 1, 2 and 3 cm between CBCT and 4DCT was 0.54~2.33, 5.16~8.06, 9.03~20.11 ml in MIP, respectively, 0.00~1.48, 0.00~8.47, 1.42~24.85 ml in MinIP, respectively and 0.00~1.17, 0.00~2.19, 0.04~3.35 ml in AVG, respectively. Conclusion : After a comparative analysis of the volumes for each nodal size, it was apparent that the CBCT images were similar to the AVG images acquired using 4DCT.

• Journal of Korean Neurosurgical Society
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• v.62 no.4
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• pp.442-449
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• 2019

Objective : Bone mineral density (BMD) is an important consideration during fusion surgery. Although dual X-ray absorptiometry is considered as the gold standard for assessing BMD, quantitative computed tomography (QCT) provides more accurate data in spine osteoporosis. However, QCT has the disadvantage of additional radiation hazard and cost. The present study was to demonstrate the utility of artificial intelligence and machine learning algorithm for assessing osteoporosis using Hounsfield units (HU) of preoperative lumbar CT coupling with data of QCT. Methods : We reviewed 70 patients undergoing both QCT and conventional lumbar CT for spine surgery. The T-scores of 198 lumbar vertebra was assessed in QCT and the HU of vertebral body at the same level were measured in conventional CT by the picture archiving and communication system (PACS) system. A multiple regression algorithm was applied to predict the T-score using three independent variables (age, sex, and HU of vertebral body on conventional CT) coupling with T-score of QCT. Next, a logistic regression algorithm was applied to predict osteoporotic or non-osteoporotic vertebra. The Tensor flow and Python were used as the machine learning tools. The Tensor flow user interface developed in our institute was used for easy code generation. Results : The predictive model with multiple regression algorithm estimated similar T-scores with data of QCT. HU demonstrates the similar results as QCT without the discordance in only one non-osteoporotic vertebra that indicated osteoporosis. From the training set, the predictive model classified the lumbar vertebra into two groups (osteoporotic vs. non-osteoporotic spine) with 88.0% accuracy. In a test set of 40 vertebrae, classification accuracy was 92.5% when the learning rate was 0.0001 (precision, 0.939; recall, 0.969; F1 score, 0.954; area under the curve, 0.900). Conclusion : This study is a simple machine learning model applicable in the spine research field. The machine learning model can predict the T-score and osteoporotic vertebrae solely by measuring the HU of conventional CT, and this would help spine surgeons not to under-estimate the osteoporotic spine preoperatively. If applied to a bigger data set, we believe the predictive accuracy of our model will further increase. We propose that machine learning is an important modality of the medical research field.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.4
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• pp.422-427
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• 2014

This study provides a method to detect blood vessels shape using image processing techniques with the help of fluoroscopy equipments, providing high precision information about vessels' location and shape of inner path. It will assist for checking and monitoring the position of operating tools during vascular interventional treatment. The blood vessels shapes are gathered with X-ray images when a fluorescent medications are injected into patient's vessel and those images are processed for getting the boundaries of vessels. Then these data are merged with real-time CT-images. These image processing systems and procedures recognize the catheter, though continued computing algorithms are very useful for observer part on the automatic control system.

• Korean Journal of Digital Imaging in Medicine
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• v.7 no.1
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• pp.33-38
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• 2005

Modern hospitals have been greatly facilitated with information technology (IT) such as hospital information system (HIS). One of the most prominent achievements is medical imaging and image data management so-called Picture Archiving and Communication Systems (PACS). Due to inevitable use of diagnostic images (such as X-ray, CT, MRI), PACS made tremendous impact not only on radiology department but also nearly all clinical departments for exchange and sharing image related clinical information. There is no doubt that better use of PACS leads to highly efficient clinical administration and hospital management. However, due to rapid and widespread acceptance of PACS storage and management of digitized image data in hospital introduces overhead and bottleneck when transferring images among clinical departments within and/or across hospitals. Despite numerous technical difficulties, financing for installing PACS is a major hindrance to overcome. In addition, a mirroring or a clustering backup can be used to maximize security and efficiency, which may not be considered as cost-effective approach because of extra hardware expenses. In this study therefore we have developed a new based on grid of distributed PACS in order to balance between the cost and network performance among multiple hospitals.

• Anatomy & Biological Anthropology
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• v.31 no.4
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• pp.133-142
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• 2018

3D histology is a imaging system for the 3D structural information of cells or tissues. The synchrotron radiation propagation phase contrast micro-CT has been used in 3D imaging methods. However, the simple phase contrast micro-CT did not give sufficient micro-structural information when the specimen contains soft elements, as is the case with many biomedical tissue samples. The purpose of this study is to develop a new technique to enhance the phase contrast effect for soft tissue imaging. Experiments were performed at the imaging beam lines of Pohang Accelerator Laboratory (PAL). The biomedical tissue samples under frozen state was mounted on a computer-controlled precision stage and rotated in $0.18^{\circ}$ increments through $180^{\circ}$. An X-ray shadow of a specimen was converted into a visual image on the surface of a CdWO4 scintillator that was magnified using a microscopic objective lens(X5 or X20) before being captured with a digital CCD camera. 3-dimensional volume images of the specimen were obtained by applying a filtered back-projection algorithm to the projection images using a software package OCTOPUS. Surface reconstruction and volume segmentation and rendering were performed were performed using Amira software. In this study, We found that synchrotron phase contrast imaging of frozen tissue samples has higher contrast power for soft tissue than that of non-frozen samples. In conclusion, synchrotron radiation propagation phase contrast cryo-microCT imaging offers a promising tool for non-destructive high resolution 3D histology.

• The Journal of Korean Society for Radiation Therapy
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• v.22 no.1
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• pp.19-24
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• 2010

Purpose: To study the efficacy of marker match with using kilovoltage (KV) X-ray among multiple image guidance that referring tree fiducial marker in radiation therapy for prostate cancer patients. Materials and Methods: KV two-dimantional images (anterior-posterior, right-left) and cone-beam CT volumetric images were acquired after setup for patients with three fiducial markers. Compare the position of the fiducial marker of reference plan computed tomography (CT) and of KV, CBCT images; then decide the shift score of X, Y, and Z. This study executed 5 times on 10 patients and analyzed the shift value. Results: In the radiation therapy using fiducial marker, The function of marker match showed the same direction tendency as the CBCT, and showed X, Y, Z difference of about 0.6, 0.7, and 0.8 (unit: mm). Conclusion: Comparing to this, the result of shift value using 2D marker match showed less than 1.0 mm difference. The function of marker match is considered more useful in time-wise and effective dose rather than CBCT. Therefore, Both methods are used to treat patients for prostate cancer.