• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.523-530
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• 2019

The purpose of this study was to obtain the K-edge images using a spectral CT system based on a photon-counting detector and implement the 3D fusion imaging using the conventional and spectral CT images. Also, we evaluated the clinical feasibility of the 3D fusion images though the quantitative analysis of image quality. A spectral CT system based on a CdTe photon-counting detector was used to obtain K-edge images. A pork phantom was manufactured with the six tubes including diluted iodine and gadolinium solutions. The K-edge images were obtained by the low-energy thresholds of 35 and 52 keV for iodine and gadolinium imaging with the X-ray spectrum, which was generated at a tube voltage of 100 kVp with a tube current of $500{\mu}A$. We implemented 3D fusion imaging by combining the iodine and gadolinium K-edge images with the conventional CT images. The results showed that the CNRs of the 3D fusion images were 6.76-14.9 times higher than those of the conventional CT images. Also, the 3D fusion images was able to provide the maps of target materials. Therefore, the technique proposed in this study can improve the quality of CT images and the diagnostic efficiency through the additional information of target materials.

• Journal of Oral Medicine and Pain
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• v.30 no.1
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• pp.107-119
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• 2005

Temporomandibular joint arthritides is divided into osteoarthritis, osteoarthrosis and polyarthritis. Because the signs, symptoms and radiographical features of osteoarthritis and osteoarthrosis are similar without arthralgia, diffenential diagnosis is difficult. Also non-radiographically change in early Osteoarthritis leads to misdiagnose. Planar bone scan and SPECT are useful to detect bone change early. This study was carried out in order to make diagnostic criteria of planar bone scan and SPECT. Three hundred and four temporomandibular joints were examined with clinical examination, computerized tomograph, planar bone scan, and SPECT. The obtained results were as follows. 1. If temporomandibular joint simple uptake ratio of patient in twenties is over 1.397%, it's condition may be osteoarthritis. And simple uptake ratio over in thirties-fourties may mean osteoarthritis. 2. It may mean osteoarthritis of temporomandibular joint that the number of coronal and transverse SPECT frame with hot spot is over four. 3. Destructive stage may goes on, if simple uptake ratio is over 1.370% in tweenties and over 1.104% in thirties-fourties. 4. If the number of coronal SPECT frame with hot spot is over four, temporomandibular joint may be on destructive stage in tweenties, thirties-fourties. And if the number of transverse SPECT frame with hot spot is over three, it may be on destructive stage in all ages. 5. When patient complains subjective arthralgia and palpation arthralgia, bone change may be more active than each arthralgia. 6. Osteoarthritis may progress gradually worse in 4.5 anamnesis. And then it may be stable gradually and turn to osteoarthrosis.

• Progress in Medical Physics
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• v.9 no.1
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• pp.47-53
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• 1998

Nuclear Medicine Images have comparatively poor spatial resolution, making it difficult to relate the functional information which they contain to precise anatomical structures. Anatomical structures useful in the interpretation of SPECT /PET Images were radiolabelled. PET/SPECT Images Provide functional information, whereas MRI mainly demonstrate morphology and anatomical. Fusion or Image Registration improves the information obtained by correlating images from various modalities. Brain Scan were studied on one or more occations using MRI and SPECT. The data were aligned using a point pair methods and surface matching. SPECT and MR Images was tested using a three dimensional water fillable Hoffman Brain Phantom with small marker and PET and MR Image was tested using a patient data. Registration of SPECT and MR Images is feasible and allows more accurate anatomic assessment of sites of abnormal uptake in radiolabeled studies. Point based registration was accurate and easily implemented three dimensional registration of multimodality data set for fusion of clinical anatomic and functional imaging modalities. Accuracy of a surface matching algorithm and homologous feature pair matching for three dimensional image registration of Single Photon Emission Computed Tomography Emission Computed Tomography (SPECT), Positron Emission Tomography (PET) and Magnetic Resonance Images(MRD was tested using a three dimensional water fill able brain phantom and Patients data. Transformation parameter for translation and scaling were determined by homologous feature point pair to match each SPECT and PET scan with MR images.

• Journal of radiological science and technology
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• v.26 no.2
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• pp.37-42
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• 2003

Purpose : Computed tomographic equipment is essential for diagnosis by means of radiation. With passage of time and development of science computed tomographic was developed time and again and in future examination by means of this equipment is expected to increase. In this connection these authors measured rate of scatter ray generation at front of lead glass for patients within control room of computed tomographic equipment room and outside of entrance door for exit and entrance of patients and attempted to ind out method for minimizing exposure to scatter ray. Material and Method : From November 2001 twenty five units of computed tomographic equipments which were already installed and operation by 13 general hospitals and university hospitals in Seoul were subjected to this study. As condition of photographing those recommended by manufacturer for measuring exposure to sauter ray was use. At the time objects used DALI CT Radiation Dose Test Phantom fot Head (${\oint}16\;cm$ Plexglas) and Phantom for Stomache(${\oint}32\;cm$ Plexglas) were used. For measurement of scatter ray Reader (Radiation Monitor Controller Model 2026) and G-M Survey were used to Survey Meter of Radical Corporation, model $20{\times}5-1800$, Electrometer/Ion Chamber, S/N 21740. Spots for measurement of scatter ray included front of lead glass for patients within control room of computed tomographic equipment room which is place where most of work by gradiographic personnel are carried out and is outside of entrance door for exit and entrance of patients and their guardians and at spot 100 cm off from isocenter at the time of scanning the object. The results : Work environment within computed tomography room which was installed and under operation by each hospital showed considerable difference depending on circumstances of pertinent hospitals and status of scatter ray was as follows. 1) From isocenter of computed tomographic equipment to lead glass for patients within control room average distance was 377 cm. At that time scatter ray showed diverse distribution from spot where no presence was detected to spot where about 100 mR/week was detected. But it met requirement of weekly tolerance $2.58{\times}10^{-5}\;C/kg$(100 mR/week). 2) From isocenter of computed tomographic equipment to outside of entrance door where patients and their guardians exit and enter was 439 cm in average, At that time scatter ray showed diverse distribution from spot where almost no presence was detected to spot with different level but in most of cases it satisfied requirement of weekly tolerance of $2.58{\times}10^{-6}\;C/kg$(100 mR/week). 3) At the time of scanning object amount of scatter ray at spot with 100 cm distance from isocenter showed considerable difference depending on equipments. Conclusion : Use of computed tomographic equipment as one for generation of radiation for diagnosis is increasing daily. Compared to other general X-ray photographing field of diagnosis is very high but there is a high possibility of exposure to radiation and scatter ray. To be free from scatter ray at computed tomographic equipment room even by slight degree it is essential to secure sufficient space and more effort should be exerted for development of variety of skills to enable maximum photographic image at minimum cost.

• Journal of the Korean Society of Radiology
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• v.9 no.2
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• pp.109-115
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• 2015

In case of a CT examinations, there is a difference in the distribution of radiation dose from that of general X-ray equipments, and it has been known to cause a great radiation exposure during the examinations. However, owing to its high reliability on the accuracy of a examinations result, its use has increased continuously. In consideration of such a circumstance, the CT equipment, radiation dose during CT examinations, diagnostic reference level, and solutions to reduce radiation dose were mentioned on the basis of previously reported data.

• Journal of Veterinary Clinics
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• v.27 no.5
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• pp.579-583
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• 2010

An 18-month-old intact male Pomeranian dog was presented because of traumatic head injury from a fall. Based on physical and neurological examination, brain injury was suspected. On plain skull radiographs, bony fragment following fracture was identified in the region of the right occipital bone. On computed tomography (CT) images, there were specific findings associated with an intracranial hemorrhage. The patient expired few hours after diagnosis, and performed necropsy. On gross findings, intracerebral hemorrhage and edema was detected and those were consistent with CT images. This report describes the clinical findings, CT imaging characteristics, necropsy findings, and histopathologic features of severe traumatic brain injury in a dog.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.355-362
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• 2010

This study determines a range of CT parameter values in Brain CT which are minimizing patient absorption dose without compromising the image quality and optimal exposure condition. We measured dose and image noise using conventional CT parameters in Brain CT. In additon, we evaluated dose, SNR and PSNR of head phantom images while changing kVp and rotation time. In this study, effectiveness of dose that was achieved from dose reproducible experiments in conventional head CT condition is determined by changing kVp and rotation time. Dose and PSNR is related to low dose-high resolution condition. In conclusion, we suggest that using proposed conditions is effective for imaging to compare with conditions proposed by the manufacturer.

• Journal of Veterinary Clinics
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• v.31 no.6
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• pp.495-501
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• 2014

The objective of this study was to evaluate the differences and reproducibility of Hounsfield unit (HU) value and volume measurements on different computed tomography (CT) scanner types and different collimations by using a gelatin phantom. The phantom consisting of five synthetic simulated calculus spanning diameters from 3.0 mm to 12.0 mm with 100 HU was scanned using a two-channel multi-detector row CT (MDCT) scanner, a four-channel MDCT scanner, and two 64-channel MDCT scanners. For all different scanner types, the thinnest possible collimation and the second thinnest collimation was used. The HU values and volumes of the synthetic simulated calculus were independently measured three times with minimum intervals of 2 weeks and by three experienced veterinary radiologists. ANOVA and Scheff$\acute{e}$ test for the multiple comparison were performed for statistical comparison of the HU values and volumes of the synthetic simulated calculus according to different CT scanner types and different collimations. The reproducibility of the HU value and volume measurements was determined by calculating Cohen's k. The reproducibility of HU value and volume measurements was very good. HU value varied between different CT scanner types, among different beam collimations. However, there was not statistically significant difference. The percent error (PE) decreased as the collimation thickness decreased, but the decrease was statistically insignificant. In addition, no statistically significant difference in the PEs of the different CT scanner types was found. It can be concluded that the CT scanner type insignificantly affects HU value and the volumetric measurement, but that a thinner collimation tends to be more useful for accurate volumetric measurement.

• Journal of the Korean Society of Radiology
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• v.10 no.6
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• pp.443-450
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• 2016

In this study, we are using a computer tomography image of the abdomen, as an experimental linear research for the image of the fatty liver patients texture features analysis and computer-aided diagnosis system of implementation using the ROC curve analysis, from the computer tomography image. We tried to provide an objective and reliable diagnostic information of fatty liver to the doctor. Experiments are usually a fatty liver, via the wavelet transform of the abdominal computed tomography images are configured with the experimental image section, shows the results of statistical analysis on six parameters indicating a feature value of the texture. As a result, the entropy, average luminance, strain rate is shown a relatively high recognition rate of 90% or more, the control also, flatness, uniformity showed relatively low recognition rate of about 70%. ROC curve analysis of six parameters are all shown to 0.900 (p = 0.0001) or more, showed meaningful results in the recognition of the disease. Also, to determine the cut-off value for the prediction of disease six parameters. These results are applicable from future abdominal computed tomography images as a preliminary diagnostic article of diseases automatic detection and eventual diagnosis.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.421-427
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• 2001

This study was performed to evaluate the embolized kidney and contralateral normal kidney using computed tomography (CT) and enhanced computed tomography. Experimental hydronephrosis was induced by ligation of unilateral ureter in Beagle dogs. Renal artery embolization was performed using selective catheterization in the hydronephrotic kidney of seven dogs and EKG, $SpO_2$, body temperature, pulse, and repiratory rate were within normal ranges during procedures. Iohexol-ethanol solution was used as embolic material. There were no dogs expired after TAE-Ra and no side effects associated with regurgitation of iohexol-ehtanol solution. Revascularization of renal artery was not found in angiography in dogs treated by TAE-RA at immediately after TAE-RA and 14 days after TAE-RA. CT showed dilation of urinary collection system and ventral displacement of spleen at 14 days after TAE-RA in one dog not treated by TAE-RA and experimental group treated by TAE-Ra. CT two month after TAE-RA showed the shrunken embolized kidney in experimental group. Transverse CT with contrast enhancement demonstrated the increase of signal intensity at thinned renal cortex in control group not treated by TAE-Ra at 30 days and 60 days, however, there was no increase of signal intensity at shrunken embolized kidney at 60 days after TAE-RA. CT was useful modality for evaluation of the morphology and the size of embolized kidney and contralateral normal kidney. Enhanced CT was availabel for the detection of revascularization of renal artery after TAE-RA in dogs with hydronephrosis. It is conclued that CT is useful modality for the monitoring of the revascularization of the renal artery after TAE-RA.