• Journal of Radiation Protection and Research
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• v.36 no.1
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• pp.23-27
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• 2011

In order to confirm feasibility of MOSFET modality in use of in.vivo dosimetry, evaluation of gonad shielding in order to minimize gonadal dose of patients undergoing radiotherapy by using MOSFET modality was performed. Gonadal dose of patients undergoing radiotherapy for rectal cancer in the department of radiation oncology of Seoul National University Hospital since 2009 was measured. 6 MV and 15 MV photon beams emitted from Varian 21EX LINAC were used for radiotherapy. In order to minimize exposed dose caused by the scattered ray not only from collimator of LINAC but also from treatment region inside radiation field, we used box.shaped lead shielding material. The shielding material was made of the lead block and consists of $7.5\; cm\;{\times}\;9.5\;cm\;{\times}5.5\;cm$ sized case and $9\;cm\;{\times}\;9.5\;cm\;{\times}\;1\;cm$ sized cover. Dosimetry for evaluation of gonad shielding was done with MOSFET modality. By protecting with gonad shielding material, average gonadal dose of patients was decreased by 23.07% compared with reference dose outside of the shielding material. Average delivered gonadal dose inside the shielding material was 0.01 Gy. By the result of MOSFET dosimetry, we verified that gonadal dose was decreased by using gonad shielding material. In compare with TLD dosimetry, we could measure the exposed dose easily and precisely with MOSFET modality.

• Journal of radiological science and technology
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• v.26 no.4
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• pp.27-32
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• 2003

To evaluate usefulness of a functional tracheobronchial phantom for interventional procedure. The functional phantom was made as a actual size with human normal anatomy used silicone and a paper clay mold. A tracheobronchial-shape clay mold was placed inside a square box and liquid silicone was poured. After the silicone was formed, the clay was removed. We measured film density and tracheobronchial angle at the human, animal and phantom, respectively. The film density of trachea part were 0.76(${\pm}0.011$) in human, 0.97(${\pm}0.015$) in animal, 0.45(${\pm}0.016$) in phantom. The tracheobronchial bifurcation part measured 0.51(${\pm}0.006$) in human, 0.65(${\pm}0.005$) in animal, 0.65(${\pm}0.008$) in phantom. The right bronchus part measured 0.14(${\pm}0.008$) in human, 0.59(${\pm}0.014$) in animal and 0.04(${\pm}0.007$) in phantom. The left bronchus were 0.54(${\pm}0.004$) in human, 0.54(${\pm}0.008$) in animal and 0.08(${\pm}0.008$) in phantom. At the stent part were 0.54(${\pm}0.004$) in human, 0.59(${\pm}0.011$) in animal and 0.04(${\pm}0.007$) in phantom, respectively. The tracheobronchial angle of the left bronchus site were $42.6({\pm}2.07)^{\circ}$ in human, $43.4({\pm}2.40)^{\circ}$ in animal and $35({\pm}2.00)^{\circ}$ in phantom, respectively. The right bronchus site were $32.8({\pm}2.77)^{\circ}$ in human, $34.6({\pm}1.94)^{\circ}$ in animal and $50.2({\pm}1.30)^{\circ}$ in phantom, respectively. The phantom was useful for in-vitro testing of tracheobronchial interventional procedure, since it was easy to reproduce.

• Journal of the Korean earth science society
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• v.41 no.6
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• pp.588-598
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• 2020

The seafloor geology of Ieodo, a submerged volcanic island, has been poorly understood, although this place has gained considerable attention for ocean and climate studies. The main purpose of the study is to understand and elucidate types, distribution patterns and provenance of the surficial sediments in and around the Ieodo area. For this purpose, 25 seafloor sediments were collected using a box-corer, these having been analyzed for grain sizes. XRD (X-ray Diffraction) analysis of fine-grained sediments was conducted for characterizing clay minerals. The peak of Ieodo exists in the northern region, while in the southern area, shore platforms occur. The extensive platform in the south results from severe erosion by strong waves. However, the northern peak still survived from differential weathering. Grain size analyses indicated that gravels and gravelly sands with skeletons and shells were distributed predominantly on the volcanic apron and shore platform. Muddy sediments were found along the Ieodo and the adjacent deeper seafloor. Based on the analysis of clay mineral composition, illites were the most abundant in fine muds, followed by chlorites and kaolinites. The ratio plots of clay minerals for the provenance discrimination suggested that the Ieodo muds were likely to be derived from the Yangtze River (Changjiang River). As a consequence, gravels and gravelly sands with bioclastics may be supplied from the Ieodo volcanic apron by erosion processes. Wave activities might play a major role in transportation and sedimentation. In contrast, fine muds were assumed to be derived from the inflow of the Yangtze River, particularly in summer. Deposition in the Ieodo area is, therefore, probably controlled by the inflow from the Changjiang Dilute Water and summer typhoons from the south.