• The Korean Journal of Nuclear Medicine
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• v.24 no.2
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• pp.237-243
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• 1990

Pulmonary embolism demands rapid and accurate diagnosis. And ventilation imaging has greatly improved the diagnostic accuracy of pulmonary embolism in addition to perfusion imaging. Agents currently used include xenon-133, krypton-81m and technetium-99m radioaerosols. However radioactive gases are compromised by availability and cost for krypton-81m, radiation dose, gamma energy and non?physiologic behaviour for xenon-133. Radioaerosols of technetium-99m componds are rapidly cleared from the lung after inhalation, and their relative low effeciency (specific radioactivity) and wide distribution of particle sizes make them also suboptimum. A new ventilation agent, Technegas is a suspension of structured graphite ellipsoids with diameter below 20nm, labelled with $^{99m}Tc$ in a carrier gas of Argon. This report describes the authors' clinical experience with Technegas. This is the first reported clinical study of this agent in Korea. A comparison of Technegas and $^{99m}Tc-DTPA$ aerosol was performed in 12 patients with various pulmonary diseases such as COPD, pulmonary tuberculosis and pleural effusion. All patients were studied with $^{99m}Tc-DTPA$ aerosol inhalation and Technegas ventilation. In both studies image quality was assessed (1) semiquantitatively by scoring bronchial and gastric activity, (2) subjectively by direct visual comparison of peripheral lung images and (3) quantitatively by computing the peripheral penetration index(PI) for each lungs. The bronchial activites were seen in 7 out of 12 cases with $^{99m}Tc-DTPA$ aerosol and in 5/12 with Technegas. The gastric activities were seen in 5/12 and 1/12 cases respectively. The average values of PI were 61.26% with $^{99m}Tc-DTPA$ aerosol and 69.20% with Technegas (p>0.05). Using $^{99m}Tc-DTPA$ aerosol, COPD patients showed deposition in the central airways with poor visualization of the peripheral areas of the lungs. In Technegas studies these phenomena were less prominent, and the examination is well tolerated by pateients and requires only a minimum of patient cooperation. With superiority of easy availability and handling, better physical characteristics and favorable Image quality, Technegas is a Promising agent for lung ventilation scanning.

• Journal of the Korean earth science society
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• v.25 no.7
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• pp.615-628
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• 2004

In order to elucidate seasonal sedimentary characteristics and depositional environment after construction of seawall on macrotidal flat, a seasonal observations of surface sediments (total 450) and sedimentation rates on 4 transects have been investigated for 2 years. The eastern area of Iwon tidal flat, has been changed from semi-closed coast to open coast by construction of seawall, shows general seasonal changes similar to characteristics of open coast type, which represented both fining and bad sorted distribution due to deposition of fine sediments under low energy condition in the summer, and relatively coarser and better sorted distribution because of erosion of fine sediments in the winter. In considering angles of transects, distribution patterns of surface sediments, the northern and southern parts of eastern tidal flat are dominantly influenced by wave and tidal effects, respectively. As time goes by, the eastern tidal flat shows coarsening-trend of surface sediments caused by direct effect of tidal current, were and typhoon. Meanwhile the western area of seawall, which has been re-formed by construction seawall, is sheltered from northwesterly seasonal wind. The seasonal change pattern of western area of seawall is slightly different from that of eastern tidal flat. Mean grain size and sorting of surface sediments during spring is finer and worse than those during summer. This seasonal change pattern maybe influenced by topographic effects caused from the construction of seawall. In consideration of all result, the transport of fine sediments in the study area, which is supplied to limited sediments, shows clockwise circulation pattern that fine sediments are transported from the eastern tidal flat to the western area of seawall because of blocking of seawall in the winter and are transported reversed direction the summer. As a result, many changes have been observed in the study area after construction of seawall; however, this change is still in progress and is expected to need continuous monitoring.