• Journal of radiological science and technology
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• v.44 no.3
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• pp.261-267
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• 2021

As the number of Coronavirus Disease-19 (COVID-19) patients increases in a global pandemic situation, the usefulness of mobile computed tomography (CT) is gaining attention. Currently, mobile CT follows the basic safety and essential performance evaluation criteria of whole-body or limited-view X-ray CT in order to obtain device approval and evaluation in the Republic of Korea. Unlike stationary CT, mobile CT is not operated in shielded areas but rather areas such as intensive care units, operating rooms, or isolation rooms. Therefore, it requires a different basic safety and essential performance evaluation standard than stationary CT. In this study, four derived basic safety evaluation criteria related to electrical, mechanical, and radiation safety were included (dose indication test, protection against stray radiation, safety measures against excessive X-rays, half-value layer measurement); and seven essential performance evaluation criteria were included (tube voltage accuracy, mAs accuracy, radiation dose reproducibility, CT number of water, noise, uniformity, and spatial resolution); total eleven basic safety and essential performance evaluation criteria were selected. This study aims to establish appropriate basic safety and essential performance evaluation criteria for simultaneously obtaining images with diagnostic value and reducing the exposure of nearby patients, medical staff, and radiologic technologists during the use of mobile CT.

• Journal of radiological science and technology
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• v.45 no.2
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• pp.127-134
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• 2022

In order to overcome the image quality limitations of the conventional C-arm, a flat panel detector (FPD) is used to enhance spatial resolution, detective quantum efficiency, frame rate, and dynamic range. Three-dimensional (3D) visualized information can be obtained from C-arm computed tomography (CT) equipped with an FPD, which can reduce patient discomfort and provide various medical information to health care providers by conducting procedures in the interventional procedure room without moving the patient to the CT scan room. Unlike a conventional C-arm device, a C-arm CT requires different basic safety and essential performance evaluation criteria; therefore, in this study, basic safety and essential performance evaluation criteria to protect patients, medical staff, and radiologists were derived based on International Electrotechnical Commission (IEC) standards, the Ministry of Food and Drug Safety (MFDS) standards in Korea, and the rules on the installation and operation of special medical equipment in Korea. As a result of the study, six basic safety evaluation criteria related to electrical and mechanical radiation safety (leakage current, collision protection, emergency stopping device, overheating, recovery management, and ingress of water or particulate matter into medical electrical (ME) equipment and ME systems: footswitches) and 14 essential performance evaluation criteria (accuracy of tube voltage, accuracy of tube current, accuracy of loading time, accuracy of current time product, reproducibility of radiation output, linearity and consistency in radiography, half layer value in X-ray equipment, focal size and collimator, relationship between X-ray field and image reception area, consistency of light irradiation versus X-ray irradiation, performance of the mechanical device, focal spot to skin distance accuracy, image quality evaluation, and technical characteristic of cone-beam computed tomography) were selected for a total of 20 criteria.

• Journal of Trauma and Injury
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• v.21 no.1
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• pp.15-21
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• 2008

Purpose: National Emergency X-Radiography Utilization Study (NEXUS) criteria and the Canadian Cervical Spine rule (CCR) are commonly used in cervical trauma patients to determine whether a plain cervical X-ray should be performed. However, plain cervical X-rays are so inaccurate that cervical spine computed tomography (CT) is often considered as a screening test. We studied the usefulness of the NEXUS criteria and the CCR for determining the need for a CT evaluation in the emergency department (ED). Methods: This prospective observational study was conducted from January 2007 to March 2008. Plain X-ray and CT scans of the cervical spine were performed on blunt trauma patients with neck pain. The relevancy of CT was examined using the NEXUS criteria and the CCR. Sensitivity, specificity, positive predicted value, and negative predicted value analyses were performed to diagnose the cervical spine injury. Results: During the study period, 284 patients were enrolled in this study. The sensitivity, specificity, positive predicted value, and negative predicted value of the NEXUS criteria were 87.5%, 1.1%, 5.0%, and 60.0% respectively, while those of the CCR were 87.5%, 8.2%, 5.3%, and 91.6%. There were two missed fracture cases when the NEXUS criteria and the CCR were applied independently, however, no cases were missed when both were applied. Conclusion: This study suggests the NEXUS and the CCR in combination can be used as a guide to CT evaluation for cervical spine injury in the ED.

• Progress in Medical Physics
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• v.32 no.1
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• pp.18-24
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• 2021

Purpose: Kilovoltage computed tomography (kV-CT) is essential for radiation treatment planning. However, kV-CT images are significantly distorted by artifacts when a metallic prosthesis is present in the patient's body. Thus, the accuracies of target delineation and treatment dose calculation are inevitably lowered. We evaluated the accuracy of the calculated doses using an image restoration method with hybrid CT, which was introduced in our previous study. Methods: A cylindrical phantom containing four metals, namely, silver, copper, tin, and tungsten, was scanned using kV-CT and megavoltage CT to produce hybrid CT images. We created six verification plans for three head and neck patients on kV-CT and hybrid CT images of the phantom and calculated their doses. The actual doses were measured with film patches during beam delivery using tomotherapy. We used the gamma evaluation method to compare dose distribution between kV-CT and hybrid CT with three gamma criteria, namely, 3%/3 mm, 2%/2 mm, and 1%/1 mm. Results: The gamma pass rates decreased as the gamma criteria were strengthened, and the pass rate of hybrid CT was higher than that of kV-CT in all cases. When the 1%/1 mm criterion was used, the difference in gamma pass rates between them was up to 13%p. Conclusions: According to our findings, we expect that the use of hybrid CT can be a suitable approach to avoid the effect of severe metal artifacts on the accuracy of dose calculation and contouring.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.2 no.2
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• pp.194-203
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• 1999

Purpose: Childhood pancreatitis has more various and somewhat different etiology than adult. Until now the analysis of severity in childhood pancreatitis were not well-known, although several studies have been made. Therefore, we studied the etiology and complications in childhood pancreatitis and analyzed whether Ranson and CT criteria could be applicated to evaluate the severity of childhood pancreatitis patients. Methods: The records of 30 patients with pancreatitis under 15 years of ages who were diagnosed in Asan medical center were reviewed. Age, sex, history, etiology, clinical features and treatment was reviewed in all patients but complications, Ranson and CT criteria were available in only 12 patients. Correlation between the number of complications and both Ranson and CT criteria were calculated with Spearman correlation coefficient. Results: 1. Median age at diagnosis was 7.3 years of age. 28 cases were acute pancreatitis and 2 cases were chronic pancreatitis. 2. Etiology: choledochal cyst(8 cases), drug (7 cases), trauma (4 cases), infection (3 cases), biliary stone or bile sludge (3 cases), idiopathic (2 cases) Hemolytic uremic syndrome, pancreatic duct obstruction, iatrogenic (1 case). 3. Local complications were ascites (5 cases), pseudocyts (4 cases) and systemic complications were hyperglycemia (4 cases), hypocalcemia (3 cases), pleural effusion (3 cases), etc. 4. Positive correlation was found between the number of complication and Ranson creteria (r=0.78, P=0.0016) and between the number of complication and CT criteria (r=0.65, P=0.015) in 13 cases. Conclusion: A trial to search the biliary duct anomaly may help to find the causes of childhood idiopathic pancreatitis, and both Ranson and CT criteria can be applicated to pediatric patients to evaluate the severity of childhood pancreatitis.

• Journal of KIISE:Software and Applications
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• v.29 no.11
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• pp.803-808
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• 2002

This paper describes automatic methods for detection of kidney and kidney tumor on abdominal CT scans. The abdominal CT images were digitalized using a film digitizer and a gray-level threshold method was used to segment the kidney. Based on texture analysis results, which were perform on sample images of kidney tumors, SEED region of kidney tumor was selected as result of homogeneity test. The average and standard deviation, which are representative statistical moments, were used to as an acceptance criteria for homogeneous test. Region growing method was used to segment the kidney tumor from the center pixel of selected SEED region using a gray-level value as an acceptance criteria for homogeneity test. These method were applied to 113 images of 9 cases, which were scanned by GE Hispeed Advantage CT scanner and digitalized by Lumisvs LS-40 film digitizer. The sensitivity was 85% and there was no false-positive results.

• Korean Journal of Radiology
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• v.25 no.3
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• pp.319-320
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• 2024

• Korean Journal of Radiology
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• v.24 no.9
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• pp.912-923
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• 2023

Objective: This study aimed to validate the risk stratification system (RSS) and biopsy criteria for cervical lymph nodes (LNs) proposed by the Korean Society of Thyroid Radiology (KSThR). Materials and Methods: This retrospective study included a consecutive series of preoperative patients with thyroid cancer who underwent LN biopsy, ultrasound (US), and computed tomography (CT) between December 2006 and June 2015. LNs were categorized as probably benign, indeterminate, or suspicious according to the current US- and CT-based RSS and the size thresholds for cervical LN biopsy as suggested by the KSThR. The diagnostic performance and unnecessary biopsy rates were calculated. Results: A total of 277 LNs (53.1% metastatic) in 228 patients (mean age ± standard deviation, 47.4 years ± 14) were analyzed. In US, the malignancy risks were significantly different among the three categories (all P < 0.001); however, CT-detected probably benign and indeterminate LNs showed similarly low malignancy risks (P = 0.468). The combined US + CT criteria stratified the malignancy risks among the three categories (all P < 0.001) and reduced the proportion of indeterminate LNs (from 20.6% to 14.4%) and the malignancy risk in the indeterminate LNs (from 31.6% to 12.5%) compared with US alone. In all image-based classifications, nodal size did not affect the malignancy risks (short diameter [SD] ≤ 5 mm LNs vs. SD > 5 mm LNs, P ≥ 0.177). The criteria covering only suspicious LNs showed higher specificity and lower unnecessary biopsy rates than the current criteria, while maintaining sensitivity in all imaging modalities. Conclusion: Integrative evaluation of US and CT helps in reducing the proportion of indeterminate LNs and the malignancy risk among them. Nodal size did not affect the malignancy risk of LNs, and the addition of indeterminate LNs to biopsy candidates did not have an advantage in detecting LN metastases in all imaging modalities.

• Journal of The Korean Association of Information Education
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• v.21 no.1
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• pp.105-114
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• 2017

Because the concepts and components of computational thinking included in the Information Education Curriculum and the Software Education Guidelines are different, it has been difficult to establish computational thinking-based software education in schools. Therefore, this study, which is based on the Delphi survey results from 39 experts, we defined computational thinking as 'computing thinking' and separated the components of computational thinking into five main categories: (1) problem definition, (2) data analysis, (3) abstraction, (4) automation, and (5) generalization. In addition, we selected software areas that are strongly related to computational thinking in the KAIE's information Curriculum Standard Model and surveyed experts to decide which computing thinking components are related to the achievement criteria of the software areas.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.2
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• pp.451-458
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• 1999

Purpose : To determine normal CT number range of parotid gland by analyzing the change by age increase and the difference among individuals and between both sexes in CT number of normal parotid gland. Materials & Methods : 134 subjects who took the CT scan between the period of Jan. 1996 and Dec. 1997 at Yonsei University, Dental Hospital were selected. Criteria for selection were that the patients must be within the normal range clinically and radiologically, and the entire parotid gland on the axial view must be shown. Among the axial views. the one showing the greatest parotid gland size was selected and its CT number was recorded. Also. CT numbers from both masseter muscle were recorded as its control. Results : There was statistically significant correlation between CT number of right and left of parotid glands and masseter muscles. With the increase of age. there is a significant decrease in the CT number of parotid gland(p<0.05). There was no statistically significant difference in CT number between sexes except the 7th decade and beyond age group of parotid gland(p>0.05). Conclusion : As age increases, CT number of parotid gland has a tendency to decrease, and there is no significant difference in the CT numbers between left and right parotid gland. Therefore in the CT scan of patients suspected of having a salivary gland disease of the parotid gland. to consider normal range of the age-dependent CT numbers of parotid gland and compare the CT numbers of the right and left parotid gland might be useful in diagnosing the disease.