• The Journal of the Korean dental association
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• v.52 no.3
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• pp.153-163
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• 2014

3-dimensional information for anatomic stucture plays a role as integral part in clinical aspect of dental practice. CBCT(cone beam computed tomography) has been accepted as useful diagnostic tool offering Volume data and images for evaluating teeth and jaws in lower radiation dose than conventional CT. CBCT equipment is essential for the quality assurance of it to ensure continued satisfactory performance and result of adequate images. Dental practitioner and oral and maxillofacial radiologist should have a responsibility and critical thinking to deliver this technology to patients in a responsible way, so that diaganostic value is maximised and radiation doses kept as low as resonably achievable. CBCT imaging modality should be used only after a review of the patient's health and imaging history and the completion of a thorough clinical examination. Clinical guidelines are systematically developed statements to assist practitioner and patient decisions about appropriate health care for specific clinical circumstances Dental practitioners should prescribe CBCT imaging only when they expect that the diagnostic yield will benefit patient care, enhance patient safety or improve clinical outcomes significantly. Knowledge of patient dose is essential for clinicians who are making the decision regarding the justification of the exposure. There are some limitation in the measurement of patient dose in CBCT for the approval and adaptation of conventinal methodolgy in CT. It is also important to ensure that doses are optimised and in line with any national and international guidelines. The higher radiation doses of CBCT compared with conventional radiography, mean that high standards must be maintained. The Quality Assurance(QA) programme should entail surveys and checks that are performed according to a regular timetable. QA programme should be maintained by staff to ensure adherence to the programme and to raise its importance among staff.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1389-1396
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• 2020

Purpose The aim of this study was to analyze several technical and clinical factors associated with the successful management of postoperative leakage by percutaneous Foley catheter placement. Materials and Methods Thirty-two patients were included in this retrospective study. Postoperative gastrointestinal leakage was diagnosed by computed tomography (CT) and the patients underwent percutaneous Foley catheter placement into the leakage site through Jackson-Pratt tubes or imaging-guided methods. Clinical success was defined as successful Foley catheter removal without symptom recurrence within 1 week and the risk factors for clinical failure were analyzed. Results In all patients, percutaneous Foley catheter placement was successfully achieved without complications. Foley catheter was placed at a median of 10 days (range, 1-68) after the confirmation of leakage on CT. Clinical success was achieved in 26 of the 32 patients (81%). Systemic comorbidity (p < 0.001) and failed oral intake (p = 0.015) were the statistically significant risk factors for clinical failure. Conclusion Percutaneous Foley catheter placement can be considered an effective approach for the management of postoperative bowel leakage. The presence of systemic comorbidity and successful oral diet after Foley catheter placement are significant factors for successful clinical recovery.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.sup1
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• pp.130-133
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• 2008

Adrenal tumors are increasingly detected by widespread use of anatomical imaging such as a, MRI, etc. For these adrenal tumors, differentiation between malignancy and benignancy is very important. In diagnostic assessment of adrenal tumor, $^{18}F-FDG$ PET and PET-CT have been reported to have high diagnostic performance, especially, very excellent performance in evaluation of adrenal metastasis in the oncologic patient. In cases of adrenal incidentalomas, $^{18}F-FDG$ PET or PET-CT is helpful if a or chemical-shift MRI is inconclusive. $^{18}F-FDG$ PET and PET-CT may be applied to the patients with MIBG-negative pheochromocytomas. In summary, $^{18}F-FDG$ PET and PET-CT are expected to be effective diagnostic tools in the management of adrenal tumor.

• Korean Journal of Radiology
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• v.21 no.7
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• pp.919-924
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• 2020

Objective: The current study reported a case series to illustrate the early computed tomography (CT) findings of coronavirus disease 2019 (COVID-19) in pediatric patients. Materials and Methods: All pediatric patients who were diagnosed with COVID-19 and who underwent CT scan in Zhongnan Hospital of Wuhan University from January 20, 2020 to February 28, 2020 were included in the current study. Data on clinical and CT features were collected and analyzed. Results: Four children were included in the current study. All of them were asymptomatic throughout the disease course (ranging from 7 days to 15 days), and none of them showed abnormalities in blood cell counts. Familial cluster was the main transmission pattern. Thin-section CT revealed abnormalities in three patients, and one patient did not present with any abnormal CT findings. Unilateral lung involvement was observed in two patients, and one patient showed bilateral lung involvement. In total, five small lesions were identified, including ground-glass opacity (n = 4) and consolidation (n = 1). All lesions had ill-defined margins with peripheral distribution and predilection of lower lobe. Conclusion: Small patches of ground-glass opacity with subpleural distribution and unilateral lung involvement were common findings on CT scans of pediatric patients in the early stage of the disease.

• Korean Journal of Clinical Pharmacy
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• v.26 no.1
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• pp.40-45
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• 2016

Objective: The increasing use of imaging examinations such as computed tomography (CT) results in increased contrast media use, which increases contrast media-induced adverse reactions (AR). This study investigated the risk factors of ARs to nonionic iodinated contrast media. Methods: This study evaluated patients who were administered iodinated contrast media during CT scanning in Yeouido St. Mary's Hospital in Seoul, Korea in 2012. Among the subjects, those with contrast media-induced ARs were classified as the AR group. The control group included individuals without ARs who were selected through simple random sampling. The effects of sex, age, contrast media type and dose, CT region, previous contrast media administration, allergy history, and comorbidity were analyzed in the AR and control groups. Results: Multivariate logistic regression analyses were performed to evaluate the identified AR risk factors in 103 subjects in the AR group and 412 subjects in the control group. The results confirmed that the risk of developing ARs was significantly higher in females [odds ratio (OR): 2.206; 95% confidence interval (CI): 1.353-3.598], in individuals administered Iohexol (OR: 9.981; 95% CI: 2.361-42.193), in individuals with an allergy history (OR: 3.982; 95% CI: 1.742-9.101), and in individuals with comorbid asthma (OR: 6.619; 95% CI: 1.377-31.826). Most of the ARs were mild and immediate. Conclusion: In patients who were administered contrast media during CT scans, female gender, Iohexol use, allergy history, and asthma were risk factors for ARs. Therefore, special care is required for patients with such risk factors to prevent ARs.

• Radiation Oncology Journal
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• v.30 no.1
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• pp.36-42
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• 2012

Purpose: To evaluate the radial displacement of clinical target volume in the patients with node negative head and neck (H&N) cancer and to quantify the relative positional changes compared to that of normal healthy volunteers. Materials and Methods: Three node-negative H&N cancer patients and five healthy volunteers were enrolled in this study. For setup accuracy, neck thermoplastic masks and laser alignment were used in each of the acquired computed tomography (CT) images. Both groups had total three sequential CT images in every two weeks. The lymph node (LN) level of the neck was delineated based on the Radiation Therapy Oncology Group (RTOG) consensus guideline by one physician. We use the second cervical vertebra body as a reference point to match each CT image set. Each of the sequential CT images and delineated neck LN levels were fused with the primary image, then maximal radial displacement was measured at 1.5 cm intervals from skull base (SB) to caudal margin of LN level V, and the volume differences at each node level were quantified. Results: The mean radial displacements were 2.26 (${\pm}1.03$) mm in the control group and 3.05 (${\pm}1.97$) in the H&N cancer patients. There was a statistically significant difference between the groups in terms of the mean radial displacement (p = 0.03). In addition, the mean radial displacement increased with the distance from SB. As for the mean volume differences, there was no statistical significance between the two groups. Conclusion: This study suggests that a more generous radial margin should be applied to the lower part of the neck LN for better clinical target coverage and dose delivery.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.215-221
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• 2023

Among brain CT scan conditions including the lens, the tube voltage was changed to 80, 100, and 120 kVp and applied. The change in dose was analyzed using lead, lead goggles and barium sulfate silicon shielding materials, and the degree of influence of the shielding materials on image quality was compared and analyzed by applying the SNR, CNR, and SSIM index analysis methods. As a result, it was analyzed that although the dose was reduced by applying all shielding materials, the difference in dose reduction was not large (P > 0.05). In addition, as for the change in image quality due to the application of the shielding material, SNR and CNR were the highest when lead goggles were applied, and the structural similarity was measured to be the best as it was closest to the reference value of 1 in SSIM analysis. Therefore, based on the results of this study, it is thought that if more diverse shielding materials and clinical test results are derived and applied, it will be helpful for the clinical application criteria in the case of shielding utilization inspection.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.214-227
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• 2013

Computed tomographic scan as a screening procedures in asymptomatic individuals has seen a steady increase with the introduction of multiple-raw detector CT scanners. This report provides a brief review of the current controversy surrounding CT cancer screening, with a focus on the radiation induced cancer risks and clinical efficacy. 1. A large study of patients at high risk of lung cancer(the National Lung Screening Trial[NLST]) showed that CT screening reduced cancer deaths by 20%(1.33% in those screened compared with 1.67% in those not screened). The rate of positive screening tests was 24.2% and 96.4% of the positive screening results in the low-dose CT group were false-positive. Radiation induced lung cancer risk was estimated the most important in screening population because ERR of radiation induced lung cancer does not show the decrease with increasing age and synergistic connection between smoking and radiation risk. Therefore, the radiation risk may be on the same order of magnitude as the benefit observed in the NLST. Optimal screening strategy remain uncertain, CT lung cancer screening is not yet ready for implementation. 2. Computed tomographic colonography is as good as colonoscopy for detecting colon cancer and is almost as good as colonoscopy for detecting advanced adenomas, but significantly less sensitive and specific for smaller lesions and disadvantageous for subsequent therapeutic optical colonoscopy if polyps are detected. The average effective dose from CT colonography was estimated 8-10 $mS{\nu}$, which could be a significant dose if administered routinely within the population over many years. CT colonography should a) achieve at least 90% sensitivity and specificity in the size category from 6 and 10 mm, b) offer non-cathartic bowl preparation and c) be optimized and standardized CT parameters if it is to be used for mass screening. 3. There is little evidence that demonstrates, for whole-body scanning, the benefit outweighs the detriment. This test found large portion of patient(86~90.8%) had at least one abnormal finding, whereas only 2% were estimated to have clinically significant disease. Annual scans from ages 45 to 75 years would accrue an estimated lifetime cancer mortality risk of 1.9%. There is no group within the medical community that recommends whole-body CT. No good studies indicate the accuracy of screening CT, at this time. The benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established. These areas need further research. Therefore wild screening should be avoided.

• The Journal of the Korean bone and joint tumor society
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• v.14 no.2
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• pp.86-94
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• 2008

$^{18}F$-FDG PET/CT has led to advancement in diagnostic imaging, providing correlation of both physiology and anatomic information, and to new and innovative ways to utilize PET/CT imaging for the evaluation of musculoskeletal tumors. Recently, the most widely utilized musculoskeletal application of PET/CT imaging is for the detection and characterization of bone metastases, staging and restaging of primary malignant bone tumors and soft tissue sarcomas. And it is also useful in evaluating response to therapy for malignant musculoskeletal tumors and in detecting local recurrences or distant metastases during follow up. The future likely holds even more unique and potentially quite useful applications of PET/CT imaging for primary bone and soft tissue tumors. This article will review the useful applications of $^{18}F$-FDG PET/CT imaging for evaluating musculoskeletal tumors.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.2
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• pp.361-368
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• 1994

Radiographic planning is needed for implant placement in order to determine implant length, jaw bone volume, anatomical stucture and so on. Radiographic examination includes conventional radiography, conventional tomography and CT scan. The most accurate mesurement can be obtained from CT scan. For the cross-sectional view of mandible, CT scan reconstruction is generally needed. But the cross-sectional view of mandible can be reformed by personal computer. This study was performed to examine the clinical usefulness of reformed image using personal computer in comparison with CT scan reconstructed image. CT axial slices of 4 mandibles of 4 volunteers were used. Digital imaging system was composed of Macintosh Ⅱ ci computer, high resolution Sony XC-77 CCD camera, Quick Capture frame grabber board and 'NIH Image' program. Seven reconstructed cross-sectional images within CT machine(CT group) were obtained. And seven reformed cross-sectional images(PC group) after digitization of CT axial slices into the personal computer were obtained. PC group was compared with CT group in the objective and subjective aspects. The results were as follow: 1. Measurement of mandibular height & width in both group showed insignificant difference(P>0.05). 2. Subjective assessment of the mandibular canal in both group showed insignificant difference(P>0.05). 3. Image reformation using personal computer could provide panoramic view, which could not be obtained in CT scan reconstruction.