• Korean Journal of Radiology
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• v.22 no.1
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• pp.97-105
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• 2021

Objective: The present study aimed to investigate the association between myocardial blood flow (MBF) quantified by dynamic CT myocardial perfusion imaging (CT-MPI) and the increments in heart rate (HR) after stress in patients without obstructive coronary artery disease. Materials and Methods: We retrospectively included 204 subjects who underwent both dynamic CT-MPI and coronary CT angiography (CCTA). Patients with more than minimal coronary stenosis (diameter ≥ 25%), history of myocardial infarction/revascularization, cardiomyopathy, and microvascular dysfunction were excluded. Global MBF at stress was measured using hybrid deconvolution and maximum slope model. Furthermore, the HR increments after stress were recorded. Results: The median radiation dose of dynamic CT-MPI plus CCTA was 5.5 (4.5-6.8) mSv. The median global MBF of all subjects was 156.4 (139.8-180.4) mL/100 mL/min. In subjects with HR increment between 10 to 19 beats per minute (bpm), the global MBF was significantly lower than that of subjects with increment between 20 to 29 bpm (153.3 mL/100 mL/min vs. 171.3 mL/100 mL/min, p = 0.027). This difference became insignificant when the HR increment further increased to ≥ 30 bpm. Conclusion: The global MBF value was associated with the extent of increase in HR after stress. Significantly higher global MBF was seen in subjects with HR increment of ≥ 20 bpm.

• The Journal of the Korea Contents Association
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• v.11 no.4
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• pp.244-252
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• 2011

This study was to estimate the radiation dose associated with 64-slice multidetector CT(MDCT) in clinical practice and quantify the potential cancer risk associated with these examinations. Lifetime attributable risks(LAR) were estimated with models developed in the national Academies' Biological Effects of Ionizing Radiation VII report. Mean effective dose were 1.48mSv in Brain axial scan, 7.66mSv in chest routine contrast, 12.17mSv in coronary angiogram, 24.52mSv in Dynamic abdomen scan. LAR estimates for brain routine varied from 1 in 7463 for man to 1 in 4926 for women. In chest routine with contrast, LAR varied from 1 in 1449 for men to 1 in 952. LAR of Abdomen dynamic CT varied from 1 in 453 for men to 1 in 298 for women. So, 64-slice MDCT scan is associated with non-negligible LAR of cancer. Doses can be reduced by careful attention to scanning protocol.

• The Journal of the Korea Contents Association
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• v.12 no.9
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• pp.270-279
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• 2012

This paper explores CT findings of a rabbit brain infection model injected with Escherichia coli and investigates the changes in Hounsfield unit (HU) of arterial blood over time. The brain infection model was produced by injecting E. coli $1{\times}10^7$ CFU/ml, 0.1 ml through the burr hole in the calvarium; 2~3 mm in depth from the dura mater, and contrast-enhanced CT, dynamic CT and arterial blood CT images were gained. It was found that various brain infections such as brain abscess, ventriculitis and meningitis. The CT image of brain abscess showed a typical pattern which the peripheral area was strongly contrast-enhanced while the center was weakly contrast-enhanced. The CT image of ventriculitis showed a strong contrast-enhancement along the lateral ventricle wall, and the CT image of meningitis showed a strong contrast-enhancement in the area between the telencephalon and the diencephalon. In dynamic CT images, the HU value of the infection core before injecting contrast medium was $31.01{\pm}3.55$. By 10 minutes after the injection, the value increased gradually to $40.36{\pm}3.76$. The HU value in the areas of the marginal rim where was hyper-enhanced showed $47.23{\pm}3.12$ before contrast injection, and it increased to $63.59{\pm}3.31$ about 45 seconds after the injection. In addition, the HU value of the normal brain tissue opposite to the E. coli. injected brain was $39.01{\pm}3.24$ before the injection, but after the contrast injection, the value increased to $49.01{\pm}4.29$ in about 30 seconds, and then it showed a gradual decline. In the arterial blood CT, the HU value before the contrast injection was $87.78{\pm}6.88$, and it increased dramatically between 10 to 30 seconds until it reached a maximum value of $749.13{\pm}98.48$. Then it fell sharply to $467.85{\pm}62.98$ between 30 seconds to 45 seconds and reached a plateau by 60 seconds. Later, the value showed a steady decrease and indicated $188.28{\pm}25.03$ at 20 minutes. Through this experiment, it was demonstrated that the brain infection model can be produced by injecting E. coli., and the characteristic of the infection model can be well observed with contrast-enhanced CT scan. The dynamic CT scan showed that the center of the infection was gradually contrast-enhanced, whereases the peripheral area was rapidly contrast-enhanced and then slowly decreased. As for arterial blood, it increased significantly between 10 seconds to 30 seconds after the contrast medium injection and decreased gradually after reaching a plateau.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.376-378
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• 2002

This work was carried out to evaluate the basic performances for 4D CT, which employed continuously rotating conebeam. The performances were evaluated with the same method as the conventional CT, because the standard method of evaluating 4D CT has not yet been established, and we think this result was helpful to establish it. 4D CT can give dynamic volume imaging data continuously and with high-speed. The results were isotropic except for the evaluation of distortion in which small distortions gradually appeared as coming off the center of phantom in longitudinal direction.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.370-374
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• 2009

In this paper, we presents a new cone beam computerized tomography (CB CT) system for the reconstruction of 3 dimensional dynamic images. The system using cone beam has less the exposure of radioactivity than fan beam, relatively. In the system, the reconstruction 3-D image is reconstructed with the radiation angle of X-ray in the image processing unit and transmitted to the monitor. And in the image processing unit, the Three Pass Shear Matrices, a kind of Rotation-based method, is applied to reconstruct 3D image because it has less transcendental functions than the one-pass shear matrix to decrease a time of calculations for the reconstruction 3-D image in the processor. The new system is able to get 3~5 3-D images a second, reconstruct the 3-D dynamic images in real time.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.543-547
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• 2016

Acute stroke is a one of common disease that require fast diagnosis and treatment to save patients life. however, the acute stroke may cause lifelong disability due to brain damage with no prompt surgical procedure. In order to diagnose the Stroke, brain perfusion CT examination and possible rapid implementation of 3D angiography has been widely used. However, a low-dose technique should be applied for the examination since a lot of radiation exposure to the patient may cause secondary damage for the patients. Therefore, the degradation of the measured CT images may interferes with a clinical check in that blood vessel shapes on the CT image are significantly affected by gaussian noise. In this study, we employed the spatio-temporal technique to analyze dynamic (brain perfusion) CT data to improve an image quality for successful clinical diagnosis. As a results, proposed technique could remove gaussian noise successfully, demonstrated a possibility of new image segmentation technique for CT angiography. Qualitative evaluation was conducted by skilled radiological technologists, indicated significant quality improvement of dynamic CT images. the proposed technique will be useful tools as a clinical application for brain perfusion CT examination.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.4
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• pp.15-21
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• 2002

This paper presents parallel operation of ZVT(Zero Voltage Transition) FUll Bridge Converter with Dynamic Current Shared Inductor. In the conventional method, CT(Current Transformer) have been used tn share the load current equally with converters. In this system, at parallel operation of ZVT Full Bridge Converter, dynamic current shared inductor divides the same current of unit converter and ZVT circuit aids to high efficiency. Superiority of the characteristics is verified through the experiment with a 2[㎾], 50[㎑] prototype converter.

• Macromolecular Research
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• v.14 no.4
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• pp.416-423
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• 2006

The dynamic mechanical thermal properties of poly(hexamethylene terephthalate) (PHT), poly(1,4-cyclohexylenedimethylene terephthalate) (PCT) and their P(HT-co-CT) random copolymers in the amorphous state were examined as a function of temperature and frequency. All the samples exhibited two main relaxation processes in the plot of tan ${\delta}$ versus temperature: the primary ${\alpha}$-relaxation associated with the glass transition and the secondary ${\beta}$-relaxation attributed to the local segmental motions of mostly cyclohexylene rings for PCT and to cooperative motions of methylene, carboxyl, and phenylene groups for PHT. Both ${\alpha}$- and ${\beta}$-relaxation temperatures increased with increasing CT content. The activation energy of the ${\alpha}$-relaxation increased with increasing CT content, whereas that of the ${\beta}$-relaxation decreased. The sub-glassy secondary ${\beta}$-relaxation processes of PCT and PHT were investigated in terms of the cooperativity of main-chain segmental motions.

• Journal of Acupuncture Research
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• v.22 no.2
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• pp.211-217
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• 2005

Objectives : Terminal stage cancer patient from primary hepatocellular carcinoma metastasized into lungs was administered with cultivated wild ginseng herbal acupuncture for 5 months and observed progression. Methods : Cultivated wild ginseng herbal acupuncture was administered 5 times a week at about 150cc dosage per week. Dynamic CT was taken and interpreted at a university hospital. Results : Above patient was diagnosed with hepatocellular carcinoma and received one procedure of lobectomy and three procedures of TACE, but because of metastasis, chance of improvement was very obscure. Intensive treatment of cultivated wild ginseng herbal acupuncture five times a week for five months in association with moxibustion was done on the patient. Near elimination of the cancer cells metastasized into lungs were confirmed in terms of radiological impression through dynamic CT. Conclusion: From the results obtained in this study, cultivated wild ginseng herbal acupuncture can be an effective measure against terminal stage cancer. But this is a single case study and lack of extensive follow-up must be compensated by further researches.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.3
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• pp.985-989
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• 2012

Objective: To make sure the feasibility with $^{18F}FDG$ PET/CT to guided dynamic intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma patients, by dosimetric verification before treatment. Methods: Chose 11 patients in III~IVA nasopharyngeal carcinoma treated with functional image-guided IMRT and absolute and relative dosimetric verification by Varian 23EX LA, ionization chamber, 2DICA of I'mRT Matrixx and IBA detachable phantom. Drawing outline and making treatment plan were by different imaging techniques (CT and $^{18F}FDG$ PET/CT). The dose distributions of the various regional were realized by SMART. Results: The absolute mean errors of interest area were $2.39%{\pm}0.66$ using 0.6cc ice chamber. Results using DTA method, the average relative dose measurements within our protocol (3%, 3 mm) were 87.64% at 300 MU/min in all filed. Conclusions: Dosimetric verification before IMRT is obligatory and necessary. Ionization chamber and 2DICA of I'mRT Matrixx was the effective dosimetric verification tool for primary focal hyper metabolism in functional image-guided dynamic IMRT for nasopharyngeal carcinoma. Our preliminary evidence indicates that functional image-guided dynamic IMRT is feasible.