• Journal of radiological science and technology
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• v.32 no.1
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• pp.95-99
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• 2009

The purpose of this research is to seek SPAIR's reversal time (TI) which satisfies two conditions ; maintaining the suppression ability of fat tissue and simultaneously minimizing the inhomogeneity of fat tissue in T2 high-speed spin echo 3.0T magnetic resonance image (MRI) of the brain, and to compare SPAIR with STIR which is fat-suppression technique. The reversal times (TI) of SPAIR protocol are set to 1/2, 1/3, 1/6 and 1/12 of SPAIR TR (420 msec), namely 210 msec (8 people), 140 msec (26 people), 70 msec (26 people) and 35 msec (18 people) and STIR TI is set with 250 msec (26 people). With these parameter sets, we acquired the axis direction 104 images of the brain. In ROI ($50\;mm^2$) of output image, signal intensities of the fatty tissue, the muscular tissue, and the background were measured and the CNRs of fatty tissue and the muscular tissue were calculated. The inhomogeneity of the fatty tissue is SD/mean, where SD is the standard deviation and 'mean' is a average fatty tissue signal. Consequently, SPAIR TI is determined on either 1/3 or 1/6 of TR (420 ms) ; 140 ms or 70 ms. Because the difference of statistics in fat-suppression ability and inhomogeneity of fatty tissue is very small (p < 0.001), Selecting 140 ms seems to be better choice for the image quality. Meanwhile, Comparing SPAIR (TI : 140 ms) with STIR, the fat-suppression is not able to be considered statistically (p < 0.252), but the image quality is able to be considered statistically (p < 0.01). In conclusion, SPAIR is better than STIR in the image quality.

• Journal of radiological science and technology
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• v.32 no.2
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• pp.177-182
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• 2009

Purpose : This study presents the optimization of flip angle (FA) to obtain higher contrast to noise ratio (CNR) and lower specific absorption rate (SAR). Materials and Method : T1-weighted images of the cerebrum of brain were obtained from 50$^\circ$ to 130$^\circ$ FA with 10$^\circ$ interval. Signal to noise ratios (SNRs) were calculated for white matter (WM), gray matter (GM), and background noise. The proper FA was analyzed by T-test statistics and Kruskal-wallis analysis using R1 = 1- exp ($\frac{-TR}{T1}$) and Ernst angle cos $\theta$ = exp ($\frac{-TR}{T1}$). Results : The SNR of WM at 130$^\circ$ FA is approximately 1.6 times higher than the SNR of WM at 50$^\circ$. The SNR of GM at 130$^\circ$ FA is approximately 1.9 times higher than the SNR of GM at 50$^\circ$. Although the SNRs of WM and GM showed similar trends with the change of FA values, the slowdown point of decrease after linear fitting were different. While the SNR of WM started decreasing at 120$^\circ$ FA, the SNR of GM started decreasing at less than 110$^\circ$. The highest SNRs of WM and GM were obtained at 130$^\circ$ FA. The highest CNRs, however, were obtained at 80$^\circ$ FA. Conclusion : Although SNR increased with the change of FA values from 50$^\circ$ to 130$^\circ$ at 3T SE T1WI, CNR was higher at 80$^\circ$ FA than at the usually used 90$^\circ$ FA. In addition, the SAR was decreased by using smaller FA. The CNR can be increased by using this optimized FA at 3T MR SE T1WI.

• Journal of radiological science and technology
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• v.39 no.2
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• pp.135-142
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• 2016

The purpose of this study is to evaluate propriety of using SID 180cm at Chest PA examination and to find effect of geometrical cause to the image. XGEO-GC80, INNOVISION-SH, CXDI-40EG detector and a chest phantom designed self-production was used for this study. Images were acquired at SID 180cm with changing the factor OID as 0, 75 and 83mm and were analyzed by Centricity Radiography RA1000 PACS system. Statistical program was used the SPSS (Version 22.0, SPSS, Chicago, IL, USA), p-value(under 0.05) was considered to be statistically significant. In OID 0 mm was enlarged about 2.7~3.5 mm than the actual degree of the HS, BS of phantom in all equipments. Compared with the calculated magnification has been expanded 1.6~2.8% when viewed. The OID 75 mm with OID 83 mm was extended from the CS and BS 6~8 mm range. Compared to the calculated values, the measured values are expanded from 6.1 to 7.9%. CS and BS according to the OID change showed a statistically significant difference (p<0.05) among each group, the post-analysis only OID 0 mm group appeared as an independent group, 75 mm and 83 mm are separated in the same group It was. But had no statistically significant difference could change depending on the OID (p>0.05), post-mortem analysis showed, both in the same group. Heart sizes appears larger than actual size 6~8 mm at chest PA examination which is enlarged 6.1~7.9% more than the actual theoretical value. We can find magnification of the image because of the increase of the OID due to technical limitations between cover of standing detector and the image plate. so we suggest to have occurred between them when considering the need to adjust the equipment installed by the SID to match the characteristics of the equipment.

• Radiation Oncology Journal
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• v.23 no.3
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• pp.169-175
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• 2005

Purpose: Although computed tomography (CT) simulators are commonly used in radiation therapy department, many Institution still use conventional CT for treatments. In this study the setup errors that occur during simulation, CT scan (diagnostic CT scanner), and treatment were evaluated for the twenty one breast cancer patients. Materials and Methods: Errors were determined by calculating the differences in isocenter location, SSD, CLD, and locations of surgical clips implanted during surgery. The anatomic structures on simulation film and DRR image were compared to determine the movement of isocenter between simulation and CT scan. The isocetner point determined from the radio-opaque wires placed on patient's surface during CT scan was moved to new position if there was anatomic mismatch between the two images Results: In 7/21 patients, anatomic structures on DRR Image were different from the simulation Image thus new isocenter points were placed for treatment planning. The standard deviations of the diagnostic CT setup errors relative to the simulator setup in lateral, longitudinal, and anterior-posterior directions were 2.3, 1.6, and 1.6 mm, respectively. The average variation and standard deviation of SSD from AP field were 1.9 mm and 2.3 mm and from tangential fields were 2.8 mm and 3.7 mm. The variation of the CLD for the 21 patients ranged from 0 to 6 mm between simulation and DRR and 0 to 5 mm between simulation and treatment. The group systematic errors analyzed based on clip locations were 1.7 mm in lateral direction, 2.1 mm in AP direction, and 1.7 mm in SI direction. Conclusion: These results represent that there was no significant differences when SSD, CLD, clips' locations and isocenter locations were considered. Therefore, it is concluded that when a diagnostic CT scanner is used to acquire an image, the set-up variation is acceptable compared to using CT simulator for the treatment of breast cancer. However, the patient has to be positioned with care during CT scan in order to reduce the setup error between simulation and CT scan.

• Journal of Oral Medicine and Pain
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• v.38 no.4
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• pp.357-366
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• 2013

This study is designed to evaluate the treatment outcome of occlusal stabilizing splint and to assess follow-up study of condylar bony changes using cone beam computed tomography(CBCT) in adolescents patients (12-19 years) with TMJ osteoarthritis(OA). 167 eroded condyles in 149 subjects were chosen among the patients who presented to the Department of Oral Medicine of Pasan National University Hospital, diagnosed as TMJ osteoarthritis by clinical exam, x-ray and CBCT from 2009 to 2012. They were treated conservatively with physical therapy, medication, behavioral therapy and occlusal stabilizing splint therapy. After average 9 months, CBCT was retaken and subjective symptoms and clinical findings were investigated. Condyle bony changes were classified by unchanged, less severe and more severe. The obtained results were as follow: 1. Pain, Noise, LOM(Limitation of motion) and MCO(Maximum comfortable opening) measurement of TMJ OA patients were markedly improved after conservative treatment. 2. In the occlusal stabilizing splint therapy group, Pain and LOM were statistically significant improved than non-occlusal stabilizing splint therapy group. 3. In the acute occlusal stabilizing splint therapy group, Pain and LOM were remarkably improved. 4. In comparison of CBCT1 and CBCT2 images, the transition of bone changes to lesser severe was most commonly in joint with erosive change. 5. In the non-occlusal stabilizing splint therapy group, the transition of condylar bone changes from erosion to more severe was many than occlusal stabilizing splint therapy group.

• Progress in Medical Physics
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• v.22 no.2
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• pp.72-78
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• 2011

The aim of this study is to evaluate the patient's setup errors in TomoTherapy (Hi-Art II, TomoTherapy, USA) Bodyfix system (Medical Intelligence, Ele-kta, Schwabmuchen, Germany) pressure in the vacuum compression, depending on and were evaluated. Bodyfix immobilization system and vacuum pressure was compression applied to the patients who received Tomotherapy thoracic and abdominal area, 21 patients were selected and TomoTehpay treatment total 477 of MVCT images were obtained. The translational (medial-lateral: ML, anterior-posterior: AP, superior-inferior: SI directions) and rolling were recorded and analyzed statistically. Using Pearson's product-moment coefficient and One-way ANOVA, the degree of correlation depending on the different vacuum pressure levels were statistically analyzed for setup errors from five groups (p<0.05). The largest average and standard deviation of systematic errors were 6.00, 5.95 mm in the AP and SI directions, respectively. The largest average of random errors were 4.72 mm in the SI directions. The correlation coefficients were 0.485, 0.244, and 0.637 for the ML-Roll, AP-Vector, and SI-Vector, respectively. SI-Vector direction showed the best relationship. In the results of the different degree of vacuum pressure in five groups (Pressure range: 30~70 mbar), the setup errors between the ML, SI in both directions and Roll p=0.00 (p<0.05) were shown significant differences. The average errors of SI direction in the vacuum pressure of 40 mbar and 70 mbar group were 4.78 mm and -0.74 mm, respectively. In this study, the correlation between the vacuum pressure and the setup-errors were statistically analyzed. The fact that setup-errors in SI direction is dependent in vacuum pressure considerly setup-errors and movement of interal organs was identified. Finally, setup-errors, and it, based on the movement of internal organs in Bodyfix system we should apply more than 50 mbar vacuum pressure. Based on the results of this study, it is suggested that accuracy of the vacuum pressure and the quantitative analysis of movement of internal organs and the tumor should be studied.

• Tuberculosis and Respiratory Diseases
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• v.43 no.1
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• pp.54-62
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• 1996

Background: $^{99m}Tc$ MIBI(Methoxyisobutylisonitrile complex), a member of the isonitrile class of coordination compounds, is a lipophilic cation presently under investigation for clinical use as myocardial perfusion imaging agent and is widely used to detect myocardial infarction. Preliminary reports indicate that $T_1$-201 accumulate in human neoplasm and several authors reported $^{99m}Tc$ MIBI may also localized in primary malignant tumor and metastatic deposits from lung cancer. We evaluated the uptake of $^{99m}Tc$ MIBI in lung cancer and localization of mediastinal and other site metastasis, and compared the benign lesion of the lung. Method: Thirty four patients of lung cancer and ten patients of benign lung lesion were studied with chest CT and $^{99m}Tc$ MIBI Lung SPECT. $^{99m}Tc$ MIBI uptake ratio was assessed by TR/NL(Lung lesion/ Normal area), HT/NL (Heart/Normal area) and HT/TR(Heart/Lung lesion). Results: 1) All lung cancer patients showed increased uptakes of $^{99m}Tc$ MIBI in malignant lung lesion and Tc-99m MIBI uptake was also increased in mediastinal and lymph node metastasis except two cases. 2) There was significant different ratio of TR/NL between malignant and benign lesion, $3.79{\pm}1.82$ and $1.67{\pm}0.63$ on planar images, respectively(p<0.001). 3) There was no significant difference of $^{99m}Tc$ MIBI uptake ratio between squamous cell carcinoma, small cell carcinoma and adeno carcinoma($3.64{\pm}1.66$, $3.57{\pm}0.72$, $4.31{\pm}2.28$ respectively). Conclusion: $^{99m}Tc$ MIBI lung SPECT was useful in the localization of tumor and mediastinal or other site metastatic lesion in lung cancer and also in the differential diagnosis between benign and malignant lesion.

• Journal of Gastric Cancer
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• v.10 no.1
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• pp.13-18
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• 2010

Purpose: Omental infarction (OI) following laparoscopy-assisted gastrectomy (LAG) for gastric cancer could become more common in the future because the indications for LAG are expected to expand. The aim of this study was to determine the clinical characteristics of OI following LAG. Materials and Methods: Three hundred ninety patients who underwent LAG for T1 or T2 gastric cancer from April 2003 to November 2007 were enrolled. OI was diagnosed by two radiologists using the patients' abdominal 16 row-detector CT scans. The clinicopathologic characteristics were retrospectively evaluated in the omental infarction (OI) group and the non-omental infarction (non-OI) group using the gastric cancer database of Dong-A University Medical Center and the medical record. Results: Nine omental infarctions (2.3%) of 390 LAGs were diagnosed. All the OIs could be discriminated from omental metastasis on the initial or follow up CT images. The location of the omental infarctions was on the epigastrium in 3 patients and in the left upper quadrant in 3 patients. The mean size of the OIs was 4.1 cm. Most patients with OI had no signs or symptoms. The body mass index of the OI group was higher than that of the non-OI group (P=0230), and OI was more common in patients who underwent total gastrectomy than in the patients who underwent subtotal gastrectomy (P=0.0011). Conclusion: Laparoscopy-assisted gastrectomy (LAG) with partial omentectomy for gastric cancer can be a cause of secondary OI. Omental infarction after LAG has different clinical characteristics and CT findings that those of other omental infarctions or postoperative omental metastases. Further multicenter study will be needed to evaluate in detail the clinical features of omental infarction after LAG.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.2
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• pp.213-230
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• 2008

The aim of this study was to analyze the initial movement and the stress distribution of each tooth and periodontal ligament during the lingual lever-arm retraction of 6 maxillary incisors using FEA. Two kinds of finite element models were produced: 2-properties model (simple model) and 24-properties model (multi model) according to the material property assignment. The subject was an adult male of 23 years old. The DICOM images through the CT of the patient were converted into the 3D image model of a skull using the Mimics (version 10.11, Materialise's interactive Medical Image Control System, Materialise, Belgium). After series of calculating, remeshing, exporting, importing process and volume mesh process was performed, FEA models were produced. FEA models are consisted of maxilla, maxillary central incisor, lateral incisor, canine, periodontal ligaments and lingual traction arm. The boundary conditions fixed the movements of posterior, sagittal and upper part of the model to the directions of X, Y, Z axis respectively. The model was set to be symmetrical to X axis. Through the center of resistance of maxilla complex, a retraction force of 200g was applied horizontally to the occlusal plane. Under this conditions, the initial movements and stress distributions were evaluated by 3D FEA. In the result, the amount of posterior movement was larger in the multi model than in the simple model as well as the amount of vertically rotation. The pattern of the posterior movement in the central incisors and lateral incisors was controlled tipping movement, and the amount was larger than in the canine. But the amount of root movement of the canine was larger than others. The incisor rotated downwardly and the canines upwardly around contact points of lateral incisor and canine in the both models. The values of stress are similar in the both simple and multi model.

• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.23-32
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• 2011

Design and Implementation of Clipcast Service via Terrestrial DMB This paper outlines the system design and the implementation process of clipcast service that can send clips of video, mp3, text, images, etc. to terrestrial DMB terminals. To provide clipcast service in terrestrial DMB, a separate data channel needs to be allocated and this requires changes in the existing bandwidth allocation. Clipcast contents can be sent after midnight at around 3 to 4 AM, when terrestrial DMB viewship is low. If the video service bit rate is lowered to 352 Kbps and the TPEG service band is fully used, then 320 Kbps bit rate can be allocated to clipcast. To enable clipcast service, the terminals' DMB program must be executed, and this can be done through SMS and EPG. Clipcast service applies MOT protocol to transmit multimedia objects, and transmits twice in carousel format for stable transmission of files. Therefore, 72Mbyte data can be transmitted in one hour, which corresponds to about 20 minutes of full motion video service at 500Kbps data rate. When running the clip transmitted through terrestrial DMB data channel, information regarding the length of each clip is received through communication with the CMS(Content Management Server), then error-free files are displayed. The clips can be provided to the users as preview contents of the complete VOD contents. In order to use the complete content, the user needs to access the URL allocated for that specific content and download the content by completing a billing process. This paper suggests the design and implementation of terrestrial DMB system to provide clipcast service, which enables file download services as provided in MediaFLO, DVB-H, and the other mobile broadcasting systems. Unlike the other mobile broadcasting systems, the proposed system applies more reliable SMS method to activate the DMB terminals for highly stable clipcast service. This allows hybrid, i.e, both SMS and EPG activations of terminals for clipcast services.