• Journal of radiological science and technology
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• v.32 no.2
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• pp.129-140
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• 2009

As CT has been increasingly used as an accurate screening tool for lung disease, radiation dose becomes an important issue for both radiographers and patients. Many researches have been done for a low-dose CT as a screening tool for early detection of asymptomatic lung diseases. From those studies, it has been reported that chest dose rate from the low-dose CT is considerably lower than from standard CT. The patient dose is determined by scanning parameters such as kVp, mAs, pitch, scan time and the radiation risk of lung in screening examination may not be negligible. Herein, we suggest that Low-dose CT is useful as a screening tool in routine clinical practice on the basis of published articles, but further study is necessary because Low-dose CT has poor sensitivity and specificity for screening early stage of lung cancer according to the results of the studies. This article is to provide a brief overview of the screening examinations by Low-dose CT.

• Journal of the Korean Society of Radiology
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• v.10 no.7
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• pp.503-510
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• 2016

Even though children are exposed to the same amount of radiation, their effective dose amount is higher than those of adults. Therefore, it is very important to reduce the amount of unnecessary radiation exposure because children have a higher radiosensitivity and a smaller body size than adults. In this study, the proposal to seek ways to reduce the amount of radiation is drawn by comparing and analyzing CT Dose Index(CTDI) on the pediatric head CT which was performed at the Busan regional hospitals, to the national diagnostic reference levels. For this, the pediatric head CT scan was conducted among the CT equipments that were installed in downtown Busan. From 2,043 children 10 years old or less who were referred to the pediatric head CT scan, targeting the 28 CT equipments in the 24 hospitals that transmit dose reports to PACS, were examined retrospectively. As a result, the average value of CTDIvol, computed tomography dose index (CTDI) of infant brain, across the hospital, was 31.18 mGy, with DLP of $444.73mGy{\cdot}cm$, which exceeded the diagnostic reference level. The lower the age, the more management is needed for radiation. However, the reality is that the CT examinations are being conducted with a dose that exceeds the reference level as the age of the aged is exceeded. For this purpose, the study seeks to determine the degree of doses of doses outside the diagnostic reference level and analyze the cause of the excess dose and devise measures to reduce the dose reduction.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.147-151
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• 2019

In chest and abdomen CT scans, the radiation exposure doses by scattering lines were measured at the eyeball and thyroid. Radiation exposure was investigated by using shielding devices. The chest and abdomen CT scan protocols used in the real examination were applied to measure and compare radiation doses before and after the use of shielding devices at the eyeball and the thyroid. The radiaton doses were measured with OSLD dosimeters. Barium, tungsten sheets, goggles and neck shields were used to protect the scattered X-ray. The chest CT scans showed respectively 3.01 mSv and 6.21 mSv at the eyeball and the thyroid by the scattered X-ray. The abdomen CT scans showed 0.55 mSv and 3.22 mSv for the eyeball and the thyroid respectively. Barium and tungsten sheets had 11% to 13% protection rates at the eyeball and the thyroid for chest CT scan, and 34% to 49% reduction in radiation dose for the abdomen CT scan. Because of the significant radiation dose, which causes cataracts and thyroid cancer by the repeated and continuous radiation exposure, for the chest and the abdomen CT scans, it is required to use shielding devices to reduce radiation dose for examinations.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.699-704
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• 2019

It is important to minimize the exposure dose during an examination and obtain good quality images at the same time. This study compared the beam harding effect according to the baseline superior orbito meatal line(SOML), orbito meatal line(OML), inferior orbito metal line(OML) and measured the exposure dose of the lens, especially in brain CT examinations, which generally apply to head diease patients. The beam harding effect assessment of each image along the baseline was performed quantitatively using the Image J program, and the exposure dose of the lens was detected by OSLDs and compared. As a result, As a result, when the SOML was used as the reference line, the dose of the lens was decreased by 85.08% at 80 kV and by 79.7% at 80 kV, compared to when IOML was used as the baseline. If the gantry angle at brain CT was parallel scan to SOML, there were no significant differences in the exposure to the lens and between the OML and IOML. Therefore, this study has shown that it is efficient to have a parallel scan on SOML as a protocol during Brain CT examinations.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.879-887
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• 2019

The purpose of this study is to establish a physiological injection protocol according to body weight, in order to minimize amount of contrast medium and optimize contrast enhancement in pediatric patients performing thoracic CT examinations. The 80 pediatric patients under the age of 10 were studied. Intravenous contrast material containing 300 mgI/ml was used. The group A injected with a capacity of 1.5 times its weight, and groups B, C and D added 5 to 15 ml of normal saline with a 10% decrease in each. The physiologic model which can be calculated by weight about amount of injection of contrast medium and normal saline, flow rate and delay time were applied. To assess image quality, measured average HU value and SNR of superior vena cava, pulmonary artery, ascending and descending aorta, right and left atrium, right and left ventricle. CT numbers of subclavian vein and superior vena cava were compared to identify the effects of reducing artifacts due to normal saline. Comparing SNR according to the contrast medium injection protocol, significant differences were found in superior vena cava and pulmonary artery, descending aorta, right and left ventricle, and CT numbers showed significant differences in all organs. In particular, B group with a 10% decrease in contrast medium and an additional injection of saline showed a low degree of contrast enhancement in groups with a decrease of more than 20%. In addition, the group injected with normal saline greatly reduced contrast enhancement of subclavian vein and superior vena cava, and the beam hardening artifact by contrast medium was significantly attenuated. In conclusion, the application of physiological protocol for injection of contrast medium in pediatric thoracic CT examinations was able to reduce artifacts by contrast medium, prevent unnecessary use of contrast medium and improve the effect of contrast enhancement.

• 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.

• The Korean Journal of Nuclear Medicine
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• v.38 no.5
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• pp.344-346
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• 2004

A 69-year-old woman was presented with progressed dysphagia, gastric soreness and weight loss during 2 months. She was performed abdomen x-ray, EGDS and abdomen CT. Abdomen x-ray demonstrated punctuate calcification on LUQ. EGDS showed an ulceroinfiltrative mass with bleeding on cardia to antrum of stomach. And CT showed diffuse gastric wall thickness with multiple calcifications. Biopsy of the stomach and esophagus during EGDS examination revealed an adenocarcinoma, with signet ring cell type, infiltrating the wall of the stomach and the distal esophagus. Then acne scan was performed a few days later. It revealed intense uptake in LUQ, corresponding to the calcium containing neoplasm seen on the abdomen x-ray, EGDS and abdomen CT. And there was no evidence of any metastatic lesion and thyroid uptake on the bone scan. There are many reports about accumulation of the tracer in extraosseous lesion, but only a few literatures were reported about gastric calcification in stomach cancer. More over, no reports showed CT images. We are performed many diagnostic examinations and found well correlation between them. The reason of gastric calcification is considered with calcium deposition within extracellular space due to hemorrhage or necrosis. Other possibility offered to explain gastric calcification have been increased blood flow and/or increased neovascularity with capillary leaks of tracer, and specific enzymatic (phosphatases) receptor binding of tracer. So, it was happened ion exchange between intracellular calcium and phosphate groups of tracer.

• Journal of Computing Science and Engineering
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• v.6 no.1
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• pp.1-11
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• 2012

Computed tomography (CT) images are widely used for the analysis of the temporal evaluation or monitoring of the progression of a disease. The follow-up examinations of CT scan images of the same patient require a 3D registration technique. In this paper, an automatic and robust registration is proposed for the rigid registration of 3D CT images. The proposed method involves two steps. Firstly, the two CT volumes are aligned based on their principal axes, and then, the alignment from the previous step is refined by the optimization of the similarity score of the image's voxel. Normalized cross correlation (NCC) is used as a similarity metric and a downhill simplex method is employed to find out the optimal score. The performance of the algorithm is evaluated on phantom images and knee synthetic CT images. By the extraction of the initial transformation parameters with principal axis of the binary volumes, the searching space to find out the parameters is reduced in the optimization step. Thus, the overall registration time is algorithmically decreased without the deterioration of the accuracy. The preliminary experimental results of the study demonstrate that the proposed method can be applied to rigid registration problems of real patient images.

• Korean Journal of Bronchoesophagology
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• v.17 no.2
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• pp.108-111
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• 2011

Epiglottic cysts cause stridor mimicking asthma and hinder intubation in surgery. A huge cyst can obstruct the airway, making laryngeal examinations impossible. Before surgery, complete visualization of the larynx is necessary for the successful excision of a cyst. If laryngeal examination fails, computed tomography (CT) scanning can provide detailed information. Virtual endoscopy based on CT data reconstruction can yield a detailed three-dimensional image of the larynx. Here, we report two cases of epiglottic cysts along with virtual endoscopic findings and surgical photographs.

• Journal of Sasang Constitutional Medicine
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• v.14 no.2
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• pp.147-152
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• 2002

One woman, Sixty three years old, suffered from chest pain, abdominal pain, nausea and vomiting for about three months. Although many examinations, brain magnetic resonance imaging(MRI), chest computed tomography(CT), abdominal CT, gastric endoscope, abdominal ultrasonography, and so forth, was performed from every point of view, those were non-significant. At first, I wrongly diagnosed her case as disease of Soumin and gave Soumin Gwakhyangjeongkisan. But she complained of diarrhea and chest discomfort. I re-diagnosed her case as Soyangin Gyeolhyung and treated with Hyeongbangdojeoksan, herbal medicine, consisted of Rhizoma Rehmanniae(生地黃), Lignum Akebiae(木通), Radix Scrophulariae(玄蔘), Semen Trichosanthis(瓜蔞仁), etc. Three weeks have passed from first visit and she did not suffered from pain. I experienced the excellent effect of Hyeongbangdojeoksan to Soyangin Gyeonlhyung.