• Journal of radiological science and technology
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• v.35 no.4
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• pp.353-360
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• 2012

Diverse designs of collimator have been applied to Single Photon Emission Computed Tomography (SPECT) according to the purpose of acquisition; thus, it is necessary to reflect geometric characteristic of each collimator for successive image reconstruction. This study carry out reconstruction algorithm for imaging system in nuclear medicine with pinhole collimator. Especially, we study to solve sampling problem which caused in the system model of pinhole collimator. System model for a maximum likelihood expectation maximization (MLEM) was developed based on the geometry of the collimator. The projector and back-projector were separately implemented based on the ray-driven and voxel-driven methods, respectively, to overcome sparse sampling problem. We perform phantom study for pinhole collimator by using geant4 application for tomographic emission(GATE) simulation tool. The reconstructed images show promising results. Designed iterative reconstruction algorithm with unmatched system model effective to remove sampling problem artefact. Proposed algorithm can be used not only for pinhole collimator but also for various collimator system of imaging system in nuclear medicine.

• Korean Journal of Radiology
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• v.2 no.1
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• pp.37-41
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• 2001

Because the tongue is superficially located and the intial manifestation of most diseases occurring there is mucosal change, lingual these lesions can be easily accessed and diagnosed without imaging analysis. Most congenital lesions of the tongue, however, can manifest as a submucosal bulge and be located in a deep portion of that organ such as its base; their true characteristics and extent may be recognized only on cross-sectional images such as those obtained by CT or MRI. In addition, because it is usually difficult to differentiate congenital lesions from other submucosal neoplasms on the basis of imaging findings alone, clinical history and physical examination should always be taken into consideration when interpretating CT and MR images of the tongue. Although the radiologic findings for congenital lesions are nonspecific, CT and MR imaging can play an important role in the diagnostic work-up of these unusual lesions. Delineation of the extent of the tumor, and recognition and understanding of the spectrum of imaging and the pathologic features of these lesions, often help narrow the differential diagnosis.

• Journal of radiological science and technology
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• v.43 no.1
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• pp.35-43
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• 2020

The purpose of this study was to study on radiologic technologist's license system and primary pathway education curriculum in the United States American (USA), focused on one case of college in Texas. We were collected and analyzed through class participation at a community college in Tarrant, interviews with professors of radiologic science and clinical radiographers, field trips, an internet search, and literature reviews. As a result, first, the American radiologic technologists license system is composed of fifteen chapters, and the professional education courses for each field are being carried out through three courses of a primary pathway, a post primary pathway and a physician extender. Second, the primary pathway courses consisted the radiography, the radiation therapy, the nuclear medicine, the magnetic resonance imaging, the sonography. Third, the USA had about 30 times more clinical practice time than Korea. In clinical practice, students had done actually examination through X-ray exposure on patients. Last radiographers in the USA was able to perform intravenous injection of radiopharmaceutical agents on patient, so that he could perform rapid examination and efficient manpower operation. This study could be used as basic data for the globalization of radiologic technologists license system in Korea.

• Imaging Science in Dentistry
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• v.30 no.4
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• pp.249-254
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• 2000

Purpose: To clarify the clinical and radiologic parameters that can be used to differentiate odontogenic keratocyst and ameloblastoma Materials and Methods: The records of 46 patients of ameloblastoma and 48 patients of odontogenic keratocyst at the Yonsei University Dental Hospital during the period of 1979 to 1995 were retrospectively reviewed. As a possible means for differentiating between the odontogenic keratocyst and ameloblastoma, the clinical parameters and the radiologic parameters were evaluated. Results: In the clinical parameters, there was no significant difference in age, sex, and sign and symptoms (p>0.05). In the radiologic parameters, there was significant difference in site, shape of the lesion, and external root resorption of adjacent teeth (p<0.05). Conclusion: The site, shape of the lesion, and external root resorption of adjacent teeth can be the parameters to differentiate odontogenic keratocyst and ameloblastoma, but a definite differentiation of these two lesions needs a more specialized imaging modality.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.2
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• pp.77-81
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• 2011

Due to the increasing quantity of health services demand a wide range of growing medical markets and hospital through advanced, diversification can meet the needs of the patient. This hospital is having the introduction of expensive medical equipment. Because of this, hospitals are struggling to operate the hospital management. Therefore, when operating at the hospital before and after introduction of the most important factor in the interests of medical equipment through the analysis is directly related to hospital operations. CT study of the local clinics, or CR 40 where members of the medical equipment with 54 points against selected practitioners and hospital visits and interviews to investigate the expected benefits of each of the members raised an average of seven months to identify revenue performance caused by interests. Raised against the expected benefits resulting benefits to the overall average 87.43% did not meet the expected benefits. The hospital plans to introduce future when reviewing the medical equipment in consideration of the characteristics of the equipment requires a more solid plan, and whether the plan is properly implemented will be needed for the institutional verification capabilities.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.2
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• pp.59-62
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• 2011

In this experiment, how DEXA(Dual-energy X-ray Absorptiometry) bone mineral density was measured using the equipment. In order to maintain the same measurement conditions, bone mineral density measurements of 10 cm thick phantom, with an actual patient at a point when examining the same conditions(100 kVp, 1 mA) and then out to the five doses of radiation and its average was calculated by dividing measured. X-ray dose rate measured at the Research Institute, Sword of the gamma survey meters calibrated MEDCOM Ltd. (Inspector GM counter tube) was used, calibration factor is 1.15. On a horizontal plane around the patient, depending on the distance was significantly reduced dose rate. In addition, orientation $0^{\circ}$ head end was higher in the direction of the highest dose rate, $0^{\circ}$ $180^{\circ}$ direction from the direction towards the higher dose rate reduced to some extent in the direction of all the $120^{\circ}$ were able to identify.

• Investigative Magnetic Resonance Imaging
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• v.21 no.4
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• pp.273-275
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• 2017

Thiemann's disease is a form of idiopathic avascular necrosis of the immature epiphyses of the phalanges of the fingers and toes. Few cases of Thiemann's disease have been reported because the disease is rare and difficult to diagnose. To the best of our knowledge, magnetic resonance imaging (MRI) findings of Thiemann's disease have not been reported. Here, we report a case of Thiemann's disease diagnosed by typical clinical symptoms and characteristic MRI findings before radiologic bony abnormalities were apparent.

• Korean Journal of Radiology
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• v.20 no.8
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• pp.1266-1274
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• 2019

Objective: To determine whether radiologic extranodal extension (ENE) appearing on pretreatment CT and MRI could predict the prognosis in patients with human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC). Materials and Methods: The study population was obtained from a historical cohort diagnosed with HPV-related OPSCC. A total of 134 OPSCC patients who had a metastatic lymph node on pretreatment CT or MRI were included, and radiologic ENE was evaluated by two experienced head and neck radiologists. Kaplan-Meier and multivariate Cox regression analyses were performed to evaluate the impact of radiologic ENE on progression-free survival (PFS). The diagnostic performance of CT and MRI for the diagnosis of ENE was also evaluated in patients who underwent neck dissection. Results: Seventy patients (52.2%) showed radiologic ENE-positive findings. Although patients showing radiologic ENE had a worse 3-year PFS (83.7% vs. 95.3%, p = 0.023), the association between radiologic ENE and PFS was not statistically significant on multivariate analysis (p = 0.141; hazard ratio, 2.68; 95% confidence interval, 0.72-9.97). CT or MRI had a sensitivity of 62%, specificity of 77.8%, and accuracy of 71.9% for predicting pathologic ENE. Conclusion: Radiologic ENE on CT or MRI did not predict poor PFS in patients with HPV-related OPSCC, although there was a trend towards worse PFS. Further studies are warranted to determine whether radiologic ENE is a useful imaging biomarker to risk-stratify patients with HPV-related OPSCC.

• Korean Journal of Radiology
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• v.24 no.11
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• pp.1167-1171
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• 2023

• Clinics in Shoulder and Elbow
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• v.25 no.3
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• pp.173-181
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• 2022

Background: Healing of the tendon itself is not always related to successful clinical outcomes after rotator cuff repair. It was hypothesized that certain radiologic factors affecting clinical outcomes could exist in case of the retear after arthroscopic rotator cuff repair (ARCR) and the radiologic factors could help predict clinical process. The purpose of this study was to identify the radiologic factors associated with clinical outcomes of the retear after ARCR. Methods: Between January 2012 and December 2019, among patients with sufficient footprint coverage for ARCR, 96 patients with Sugaya classification 4 or higher retear on follow-up magnetic resonance imaging were included. The association between clinical outcomes such as American Shoulder and Elbow Surgeons (ASES) score, Constant score and range of motion and radiologic variables such as initial tear dimension, retear dimension, variance of tear dimension, critical shoulder angle, acromial index, and acromiohumeral distance was analyzed. Results: Preoperatively, the ASES and Constant scores were 59.81±17.02 and 64.30±15.27, respectively. And at the last follow-up, they improved to 81.56±16.29 and 78.62±14.16, respectively (p<0.01 and p<0.01). In multiple linear regression analysis, the variance of the mediolateral dimension of tear had statistically significant association with the ASES and Constant scores (p<0.01 and p=0.01). Conclusions: In patients with the retear after ARCR, the variance in the mediolateral dimension of tear had significantly negative association with the clinical outcomes. This could be considered to be reference as relative criteria and needed more sample and mechanical study.