Eng-Chan Kim

Analysis of Images According to the Fluid Velocity in Time-of-Flight Magnetic Resonance Angiography, and Contrast Enhancement Angiography

In this study we evaluated that flow rate changes affect the (time of flight) TOF image and contrast-enhanced (CE) in a three-dimensional TOF angiography. We used a 3.0T MR System, a nonpulsatile flow rate model. Saline was used as a fluid injected at a flow rate of 11.4 cm/sec by auto injector. The fluid signal strength, phantom body signal strength and background signal strength were measured at 1, 5, 10, 15, 20 and 25-th cross-section in the experienced images and then they were used to determine signal-to-noise ratio and contrastto- noise ratio. The inlet, middle and outlet length were measured using coronal images obtained through the maximum intensity projection method. As a result, the length of inner cavity was 2.66 mm with no difference among the inlet, middle and outlet length. We also could know that the magnification rate is 49-55.6% in inlet part, 49-59% in middle part and 49-59% in outlet part, and so the image is generally larger than in the actual measurement. Signal-to-noise ratio and contrast-to-noise ratio were negatively correlated with the fluid velocity and so we could see that signal-to-noise ratio and contrast-to-noise ratio are reduced by faster fluid velocity. Signal-to-noise ratio was 42.2-52.5 in 5-25th section and contrast-to-noise ratio was from 34.0-46.1 also not different, but there was a difference in the 1st section. The smallest 3D TOF MRA measure was 2.51 ± 0.12 mm with a flow velocity of 40 cm/s. Consequently, 3D TOF MRA tests show that the faster fluid velocity decreases the signal-to-noise ratio and contrast-to-noise ratio, and basically it can be determined that 3D TOF MRA and 3D CE MRA are displayed larger than in the actual measurement.

Discussion on the usefulness of dose dynamic multi-leaf collimator-based plan to overcome dose limit of spinal cord in high-dose radiotherapy

In this study, the conventional plan was compared with the plan that was based on a dose dynamic multi-leaf collimator (MLC), and a dose dynamic MLC was used to evaluate its usefulness. Then, this study examined if it was possible to perform a high-dose radiation therapy by adjusting the dose limit of the spinal cord when the dose dynamic MLC-based plan was used. First of all, linear accelerator was used to compare the conventional plan with the dose dynamic MLC-based plan. Then, the study was conducted in two methods in order to examine the proper range of the shield for the spinal cord when the dose dynamic MLC was used to adjust the dose of the spinal cord. In the first method, X-omat film was used to perform film dosimetry. In the second method, radiation treatment planning (RTP) system was used to find out the proper range among 0, 3, 6, and 9 mm. When film scan was performed in the each range, respectively, from the spinal cord and under the same conditions, it was confirmed to be appropriate to use the range of 3 mm. When the RTP system was used to perform planning in the shield range of each range, respectively, from the spinal cord, dose-volume histogram (DVH) was a slight difference could be found in the region from 25% to 35%. On the contrary, no radiation exposure was found in the region of 35% or higher for all of the each range. Consequently, if MLC is selected in consideration of the planning target volume (PTV), the most proper value can be obtained by selecting the range of 3 mm. Next, the DVH was compared to examine the relationship in PTV when the each range was used for planning. All of the ranges showed the same pattern up to the point of 90%. However, the results were different in the region of higher than 90% because the dose was low for the spinal cord, and a relatively useful dose was used for PTV when the range was 3 mm.

Mössbauer Study of (Fe 0.95 Ni 0.05 ) 7 Se 8

By Mossbauer spectroscopy and x-ray measurement (Fe0.95Ni0.05)7Se8 has been studied. The crystal structure of (Fe0.95Ni0.05)7Se8 is found to be a triclinic superstructure of the NiAs sturcture while Fe7Se8 has a orthohexagonal superstructure. Abrupt changes of quadrupole shifts near 125 K for (Fe0.95Ni0.05)7Se8 suggests that the spin-rotation transition proceeds abruptly, in contrast with the gradual transition reported for Fe7Se8 with a triclinic superstructure. Isomer shifts indicate a ferrous state for the iron ions at all four states.

The Utility Evaluation of Reconstructed 3-D Images by Maximum Intensity Projection in Magnetic Resonance Mammography and Cholangiopancreatography

The aim of this study was to evaluate the utility of 3-D images by comparing and analyzing reconstructed 3-D images from fast spin echo images of MRI cholangiopancreatography (MRCP) images using maximum intensity projection (MIP) with the subtraction images derived from dynamic tests of magnetic resonance mammography. The study targeted 20 patients histologically diagnosed with pancreaticobiliary duct disease and 20 patients showing pancreaticobiliary duct diseases, where dynamic breast MR (magnetic resonance) images, fast spin echo imaged of pancreaticobiliary duct, and 3-D reconstitution images using a 1.5T MR scanner and 3.0T MR scanner were taken. As a result of the study, the signal-to-noise ratio in the subtracted breast image before and after administering the contrast agent and in the reconstructed 3-D breast image showed a high ratio in the reconstructed image of lesional tissue, relevant tissue, and fat tissue. However, no statistically meaningful differences were found in the contrast-to-noise ratio of the two images. In the case of the MRCP image, no differences were found in the ratios of the fast spin echo image and reconstructed 3-D image.

A comparative quantitative analysis of the IDEAL (iterative decomposition of water and fat with echo asymmetry and least-squares estimation) and the CHESS (chemical shift selection suppression) techniques in 3.0 T L-spine MRI

This study was conducted on 20 patients who had undergone pedicle screw fixation between March and December 2010 to quantitatively compare a conventional fat suppression technique, CHESS (chemical shift selection suppression), and a new technique, IDEAL (iterative decomposition of water and fat with echo asymmetry and least squares estimation). The general efficacy and usefulness of the IDEAL technique was also evaluated. Fat-suppressed transverse-relaxation-weighed images and longitudinal-relaxation-weighted images were obtained before and after contrast injection by using these two techniques with a 1.5T MR (magnetic resonance) scanner. The obtained images were analyzed for image distortion, susceptibility artifacts and homogenous fat removal in the target region. The results showed that the image distortion due to the susceptibility artifacts caused by implanted metal was lower in the images obtained using the IDEAL technique compared to those obtained using the CHESS technique. The results of a qualitative analysis also showed that compared to the CHESS technique, fewer susceptibility artifacts and more homogenous fat removal were found in the images obtained using the IDEAL technique in a comparative image evaluation of the axial plane images before and after contrast injection. In summary, compared to the CHESS technique, the IDEAL technique showed a lower occurrence of susceptibility artifacts caused by metal and lower image distortion. In addition, more homogenous fat removal was shown in the IDEAL technique.

The Qualitative Analysis of Single Shot Fast Spin Echo (SSFSE) and Maximum Intensity Projection (MIP) on Magnetic Resonance Cholangiopancreatography

3-dimensional magnetic resonance cholangiopancreatography (MRCP) images reconstructed using the maximum intensity projection technique were analyzed qualitatively in patients diagnosed with pancreatobiliary diseases to determine their diagnostic utility. Single shot fast spin echo (SSFSE), fast spin echo (FSE) and 3-dimensional reconstructive images were acquired from 20 patients diagnosed histologically with pancreatobiliary diseases using a 3.0T MR scanner. According to qualitative analysis, the fast spin echo images and 3-dimensional reconstructed images of the hepatic duct, gall bladder and common bile duct had a higher signal to noise ratio (SNR) than the single shot fast spin echo images. Fast spin echo images and 3-dimensional reconstructed images did not show any differences. The contrast to noise ratio of the hepatic duct, gallbladder and common bile duct on the fast spin echo images and 3-dimensional reconstructed images was higher than that of the single shot fast spin echo images. The fast spin echo images and 3-dimensional reconstructed images showed similar quality.

The Study on Mössbauer Spectroscopy of Zn 1-x Fe x O

Recently, the-semiconductor ZnO, normally n-type, doped with magnetic impurities was reported to be ferromagnetic above room temperature. Since ZnO is optically transparent, ferromagnetic Zno should a transparent magnet as well. The purpose of this study was to carry out , X-ray and magnetic-susceptibility measurements on to examine its magnetic properties and to separate the contributions of the ferromagnetic and the paramagnetic phases to the magnetization. The X-ray diffraction (XRD) data for showed a typical hexagonal structure, with no indication of a secondary phase. The magnetic hysteresis (M-H) curve at room temperature showed an obvious ferromagnetic behaviour, and the magnetic moment per Fe atom under an applied field of 0.8 T was estimated to be about , suggesting a low spin configuration of Fe ions. spectra of have been taken at various temperatures ranging from 100 to 300 K. The Mossbauer spectrum of consists of a ferromagnetic (six-Lorentzian) and a paramagnetic phase (doublet).

Magnetic Properties of Ti 0.96 Co 0.02 Fe 0.02 O 2

The samples were synthesized by using a solid state reaction. The X-ray diffraction pattern for showed a pure rutile phase with tetragonal structures. Mixtures of the proper proportions of the elements sealed in evacuated quartz ampoule were heated at for one day and then slowly cooled down to room temperature at a rate of . In order to obtain single phase material, it was necessary to grind the sample after the first firing and to press the powders into pellets before annealing them for a second time in evacuated and sealed quartz ampoule. Magnetic properties have been investigated using the vibrating sample magnetometer(VSM). Room temperature magnetic hysteresis(M-H) curve showed an obvious ferromagnetic behavior and the magnetic moment per Fe atom under the applied of 0.8T was estimated to be about . But the magnetic moment per Fe atom under the applied of 0.8T was estimated to be about without Ti-getter.

Mössbauer Study of Ti 1-x-y Co x Fe y O 2

[ ] spectra of prepared with enriched iron have been taken at various temperatures ranging from 80 to 300K. The Mossbauer spectrum of consists of a ferromagnetic (six-Lorentzian), a paramagnetic phase (doublet) and armorphous phase over all temperature ranges. Isomer shifts indicate for the ferromagnetic phase and the paramagneic phase of samples. It is noted that the magnetic hyperfine field of ferromagnetic phase had the value about 1.5 times as large as that of u-fe. The XRB data for showed mainly rutile phase with tetragonal structures without any segregation of Co and Fe into particulates within the instrumental resolution limit. The magnetic moment per (Co+Fe) atom in , under the applied field of 1T was estimated to be about which is ten times as large as that of per Co atom, suggesting a high spin configuration of Co and fe ions.