• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.21-32
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• 1999

Purpose: To evaluate the effect of variable scanning protocols of computed tomography for evaluation of pre-implant site of the mandible through the comparison of the reformatted cross-sectional images of helical CT scans obtained with various imaging parameters versus those of conventional CT scans. Materials and Methods: A dry mandible was imaged using conventional nonoverlapped CT scans with 1 mm slice thickness and helical CT scans with 1 mm slice thickness and pitches of 1.0, 1.5. 2.0, 2.5 and 3.0. All helical images were reconstructed at reconstruction interval of 1 mm. DentaScan reformatted images were obtained to allow standardized visualization of cross-sectional images of the mandible. The reformatted images were reviewed and measured separately by 4 dental radiologists. The image qualities of continuity of cortical outline. trabecular bone structure and visibility of the mandibular canal were evaluated and the distance between anatomic structures were measured by 4 dental radiologists. Results: On image qualities of continuity of cortical outline. trabecular bone structure and visibility of the mandibular canal and in horizontal measurement. there was no statistically significant difference among conventional and helical scans with pitches of 1.0. 1.5 and 2.0. In vertical measurement. there was no statistically significant difference among the conventional and all imaging parameters of helical CT scans with pitches of 1.0, 1.5, 2.0, 2.5 and 3.0. Conclusion: The images of helical CT scans with 1 mm slice thickness and pitches of 1.0, 1.5 and 2.0 are as good as those of conventional CT scans with 1 mm slice thickness for evaluation of predental implant site of the mandible. Considering the radiation dose and patient comfort, helical CT scans with 1 mm slice thickness and pitch of 2.0 is recommended for evaluation of pre-implant site of the mandible.

• Journal of Trauma and Injury
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• v.19 no.1
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• pp.28-34
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• 2006

Purpose: In maxillofacial surgery, proper preoperative diagnosis is very important in achieving good postoperative results. Although conventional CT scans are useful for visual representations of fractures, they cannot provide direct guidance for reconstructing facial bone fractures. However, the recent technology of multislice scanning has brought many clinical benefits to CT images. Direct correlations can be made between preoperative imaging data and operative planning. The aim of the current study is to evaluate the differences between conventional CT and multidetective three-dimensional CT(3D MDCT) measurements in craniofacial deformities. Methods: From January 2005 to November 2005, MDCT scans of 41 patients were evaluated by comparing them with conventional CT scans. The 3D MDCT images were assessed and reviewed by using a simple scoring system. Results: The 3D MDCT scans offered easy interpretation, facilitated surgical planning, and clarified postoperative results in malar complex fractures, mandibular fractures, and extensive maxillofacial fractures and cranioplasty. However, 3D MDCT images were not superior to conventional CT scans in the diagnosis of blowout fractures. Conclusion: In spite of its limitations, the 3D MDCT provided additional and more comprehensive information than the conventional CT for preoperative assessment of craniofacial deformities. Therefore, the 3D MDCT can be a useful tool for diagnosis and systematic treatment planning in craniofacial skeletal deformities.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.681-688
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• 2022

Dose monitoring in CT patients requires accurate dose estimation but most of the CT dose calculation tools are based on Caucasian computational phantoms. We established a library of organ dose conversion coefficients for Korean adults by using four Korean adult male and two female voxel phantoms combined with Monte Carlo simulation techniques. We calculated organ dose conversion coefficients for head, chest, abdomen and pelvis, and chest-abdomen-pelvis scans, and compared the results with the existing data calculated from Caucasian phantoms. We derived representative organ doses for Korean adults using Korean CT dose surveys combined with the dose conversion coefficients. The organ dose conversion coefficients from the Korean adult phantoms were slightly greater than those of the ICRP reference phantoms: up to 13% for the brain doses in head scans and up to 10% for the dose to the small intestine wall in abdominal scans. We derived Korean representative doses to major organs in head, chest, and AP scans using mean CTDI_vol values extracted from the Korean nationwide surveys conducted in 2008 and 2017. The Korean-specific organ dose conversion coefficients should be useful to readily estimate organ absorbed doses for Korean adult male and female patients undergoing CT scans.

• Archives of Plastic Surgery
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• v.39 no.6
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• pp.631-635
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• 2012

Background The evaluation of a breast after breast reconstruction depends on a surgeon's subjective criteria. We used computed tomography (CT) scans to obtain an objective evaluation of the postoperative results by measuring the breast volume of patients who had undergone breast reconstruction using pedicled transverse rectus abdominis myocutaneous (TRAM) flaps. This research will help in the objective postoperative evaluation of reconstructed breasts, and also in the preoperative flap size designs. Methods A total of 27 patients underwent breast reconstruction using pedicled TRAM flaps after mastectomy from September 2007 to July 2010. Of these, 10 patients who were followed up and underwent CT scans 2 or more times during the follow-up period were included in this study. We evaluated the change in breast volume over time using CT scans, and the interval breast volume change between CT scans. Results All of the 10 patients' reconstructed breasts showed a volume decrease over time. The breast volume changes in the intervals between CT scans were as follows: 5.65% decrease between the first CT and second CT scan, 2.3% decrease between the second CT and third CT scan, (statistically significant) and 1.89% decrease between the third CT and forth CT scan. (not statistically significant). Conclusions This research shows the possibility of objectively evaluating the postoperative breast volume changes. The findings will be helpful in designing the size of TRAM flaps to use on defects after mastectomy. Based on these results, we should also closely observe the reconstructed breast volume for at least 2 years.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.6
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• pp.658-665
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• 2000

Purpose : The present study was carried out to determine the diagnostic usefulness of bone scan for evaluating jaw bone extension of oral cancer. Materials and Methods : Medical records, preoperative bone scans, computerized tomographic (CT) scans, conventional radiographs, and findings of histopathologic sections of twenty patients who had been treated for oral malignant tumors by a resection of mandible and soft tissue at Chonnam University Hospital from January, 1994 to September, 1999 were analyzed. Results : In 13 cases which showed histopathologically positive, preoperative bone scans were positive in 12 (92.3%) and false negative in 1 (7.7%). Preoperative CT scans were positive in 9 (69.2%) and false negative in 4 (30.8%) of the 13 cases. Preoperative conventional radiographs were positive in 8 (61.5%) and false negative in 5 (38.5%) of the 13 cases. In 7 cases showing negative histopathologic findings, 1 (14.3%) was in CT scans and 2 (28.6%) were false positive in preoperative conventional radiographs. Conclusion : These results suggest that bone scan is more sensitive and reliable method for evaluating jaw bone extension of oral cancer than conventional radiographs or CT scans.

• Journal of Intelligence and Information Systems
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• v.13 no.1
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• pp.15-27
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• 2007

In Korea, hepatoma is the thirdly frequent cause of death from cancer occupying 17.2% among the whole deaths from cancer and the rate of death from hepatoma comes to about 21's persons per one-hundred thousand ones. This paper proposes an automatic method for the extraction of areas being suspicious as hepatoma from a CT scan and evaluates the availability as an auxiliary tool for the diagnosis of hepatoma. For detecting tumors in the internal of the liver from CT scans, first, an area of the liver is extracted from about $45{\sim}50's$ CT scans obtained by scanning in 2.5-mm intervals starting from the lower part of the chest. In the extraction of an area of the liver, after unconcerned areas outside of the ribs being removed, areas of the internal organs are separated and enlarged by using intensity information of the CT scan. The area of the liver is extracted among separated areas by using information on position and morphology of the liver. Since hepatoma is a hypervascular turner, the area corresponding to hepatoma appears more brightly than the surroundings in contrast-enhancement CT scans, and when hepatoma shows expansile growth, the area has a spherical shape. So, for the extraction of areas of hepatoma, areas being brighter than the surroundings and globe-shaped are selected as candidate ones in an area of the liver, and then, areas appearing at the same position in successive CT scans among the candidates are discriminated as hepatoma. For the performance evaluation of the proposed method, experiment results obtained by applying the proposed method to CT scans were compared with the diagnoses by radiologists. The evaluation results showed that all areas of the liver and liver tumors were extracted exactly and the proposed method has a high availability as an auxiliary diagnosis tools for the discrimination of liver tumors.

• Journal of the Korean Society of Radiology
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• v.83 no.1
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• pp.138-148
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• 2022

Purpose This study evaluated the rates and annual trends of pediatric CT scans in South Korea using a nationwide population-based database. Materials and Methods Data regarding pediatric CT scan usage between 2012 and 2017 were retrieved from the health insurance review and assessment service. Data on the age, sex, diagnosis, and the anatomical area of involved patients were also extracted. Results A total of 576376 CT examinations were performed among 58527528 children aged below 18 years (9.8 scans/1000 children), and the number of CT examinations per 1000 children was noted to have increased by 23.2% from 9.0 in 2012 to 11.0 in 2017. Specifically, the number of CT examinations increased by 32.9% for the 6-12 years of age group (7.4/1000 to 9.8/1000) and by 34.0% for the 13-18 years of age group (11.4/1000 to 15.3/1000). Moreover, majority of the CT scans were limited to the head (39.1%), followed by the extremities (32.5%) and the abdomen (13.7%). Notably, the number of extremity CT scans increased by 83.6% (2.3/1000 to 4.2/1000), and its proportion as compared to other scans increased from 25.3% to 37.7%. Conclusion CT scans in the pediatric population increased continuously from 2012 to 2017 at an annual rate of 4.4%. Therefore, physicians should balance the benefits of CT with its potential harms from associated radiation exposure in pediatric patients.

• Tuberculosis and Respiratory Diseases
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• v.80 no.4
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• pp.368-376
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• 2017

Background: A ground-glass nodule (GGN) represents early-stage lung adenocarcinoma. However, there is still no consensus for preoperative staging of GGNs. Therefore, we evaluated the need for the routine use of positron emission tomography/computed tomography (PET)/computed tomography (CT) scans and brain magnetic resonance imaging (MRI) during staging. Methods: A retrospective analysis was undertaken in 72 patients with 74 GGNs of less than 3 cm in diameter, which were confirmed via surgery as malignancy, at the Samsung Medical Center between May 2010 and December 2011. Results: The median age of the patients was 59 years. The median GGN diameter was 18 mm. Pure and part-solid GGNs were identified in 35 (47.3%) and 39 (52.7%) cases, respectively. No mediastinal or distant metastasis was observed in these patients. In preoperative staging, all of the 74 GGNs were categorized as stage IA via chest CT scans. Additional PET/CT scans and brain MRIs classified 71 GGNs as stage IA, one as stage IIIA, and two as stage IV. However, surgery and additional diagnostic work-ups for abnormal findings from PET/CT scans classified 70 GGNs as stage IA, three as stage IB, and one as stage IIA. The chest CT scans did not differ from the combined modality of PET/CT scans and brain MRIs for the determination of the overall stage (94.6% vs. 90.5%; kappa value, 0.712). Conclusion: PET/CT scans in combination with brain MRIs have no additional benefit for the staging of patients with GGN lung adenocarcinoma before surgery.

• The Journal of the Korean bone and joint tumor society
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• v.9 no.2
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• pp.162-168
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• 2003

Purpose: Primary malignant bone tumors are classified with mesenchymal sarcomas (MS) such as osteosarcoma and chondrosarcoma and small round cell sarcomas (SRS) such as Ewing's sarcoma and lymphoma. Radiological examinations for skeletal sarcoma were using MR scan in tubular bone sarcomas and CT scan in flat bone sarcomas recently. Both MR and CT scans show some findings of bone destruction and soft tissue mass but MR scans don't reveal a finding with mineralization relatively. So we investigated bone destructive pattern of skeletal sarcomas on both MR and CT scans for differentiation of MS and SRS. Materials and Methods: There are 28 MS and 26 SRS examined with MR or CT scans. The findings according to bone destructive pattern were divided to eccentric and concentric in 26 cases of tubular bone sarcomas with MR scan and 28 cases of flat bone sarcomas with CT scan. Results: MR images revealed eccentric destruction in 12 cases of 16 MS and concentric in all cases of 10 SRS (p>.01). CT images showed eccentric destruction in 10 cases of 12 MS and concentric bone destruction in 13 cases of 16 SRS (p>.01) Conclusion: The findings divided to eccentric and concentric bone destructive patterns were useful for differential diagnosis of MS from SRS on both MR and CT scans.

• Journal of Radiation Protection and Research
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• v.46 no.3
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• pp.98-105
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• 2021

Background: In recent events of the coronavirus disease 2019 (COVID-19) pandemic, computed tomography (CT) scans are being globally used as a complement to the reverse-transcription polymerase chain reaction (RT-PCR) tests. It will be important to be aware of major organ dose levels, which are more relevant quantity to derive potential long-term adverse effect, for Korean pediatric and adult patients undergoing CT for COVID-19. Materials and Methods: We calculated organ dose conversion coefficients for Korean pediatric and adult CT patients directly from Korean pediatric and adult computational phantoms combined with Monte Carlo radiation transport techniques. We then estimated major organ doses delivered to the Korean child and adult patients undergoing CT for COVID-19 combining the dose conversion coefficients and the international survey data. We also compared our Korean dose conversion coefficients with those from Caucasian reference pediatric and adult phantoms. Results and Discussion: Based on the dose conversion coefficients we established in this study and the international survey data of COVID-19-related CT scans, we found that Korean 7-year-old child and adult males may receive about 4-32 mGy and 3-21 mGy of lung dose, respectively. We learned that the lung dose conversion coefficient for the Korean child phantom was up to 1.5-fold greater than that for the Korean adult phantom. We also found no substantial difference in dose conversion coefficients between Korean and Caucasian phantoms. Conclusion: We estimated radiation dose delivered to the Korean child and adult phantoms undergoing COVID-19-related CT examinations. The dose conversion coefficients derived for different CT scan types can be also used universally for other dosimetry studies concerning Korean CT scans. We also confirmed that the Caucasian-based CT organ dose calculation tools may be used for the Korean population with reasonable accuracy.