• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.889-894
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• 2019

Upper gastrointestinal series is an examination that uses X-rays. It is important to defend against exposure to radiation during upper gastrointestinal examination because the organs, such as thyroid gland, lens, breasts, and gonads, with relatively high biological sensitivity to radiation are distributed on the examination area. We have made a whole body phantom that can change the depth of organs. radiation dose of eye, thyroid gland, breast and gonads were measured by the same procedure as the actual upper gastrointestinal examination. When performed only fluoroscopy the mean dose reduction of lens, thyroid gland, breast and gonads was 62.2%. The mean dose reduction of lens, thyroid gland, breast and gonads was 59.0% when both fluoroscopy and spot shoot were performed. Therefore, when performed upper gastrointestinal examination it was confirmed that shielding of the lens, thyroid gland, breast and gonads was effective in decreasing the exposure dose. The manufactured human phantom can be used in measuring radiation dose for deep organ because it can adjust the height corresponding to the organs located in the human body.

• Journal of Korean Ophthalmic Optics Society
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• v.4 no.1
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• pp.73-76
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• 1999

Screening of strabismus was followed in 1306 healthy elementary school students from 8 to 13 years old. The cover-uncover test with M1N GLASSES was used to screen strabismus for all of students and then we examined abnormal students by the prism cover test. Finally 16 students were strabismus. So the cover-uncover test with MIN GLASSES was a good method to screen strabismus because of easy and simple testing. The number of strabismus was 16 patients who consisted in from 10 to 13 years old, and girls(2.4%) was 3 times more than boys(0.9%). The type of 16 strabismus was only heterophoria which consisted in 8 patients of exophoria, 7 patients of esophoria and 1 patient of hyperphoria. So the rate of exophoria and esophoria was almost same. 3 patients was ametropic amblyopia by testing visual acuity, and all of patients were normal color vision by color testing.

• Journal of the Korean Geotechnical Society
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• v.33 no.12
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• pp.141-150
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• 2017

Geosynthetics are generally utilized to restrain the leakage of leachate and other contaminants during the construction of offshore waste landfill. Therefore, geosynthetic-soil interface is formed inevitably. In this study, 2 dimensional numerical analysis is performed to assess the dynamic behaviour of the offshore waste landfill including geosynthetic-soil interface. Offshore waste landfill can be divided into rubble mound revetment and retaining wall types and analyzed on each type. Effective stress analysis is conducted to consider the variation of pore water pressure and axial force and shear displacement of the interface are compared based on the characteristics of seismic frequency. Consequently, retaining wall type demonstrates more stable behavior against liquefaction potential and favorable forces and shear displacement.

• Journal of radiological science and technology
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• v.33 no.2
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• pp.127-132
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• 2010

The purpose of this study is to measure scattered ray which is occurred except for Z-axis range of the detector in MDCT's iso-center and present the basic data about the standard for reduction of scattered ray. The development of MDCT brings out the enlargement of beam thickness to the patient's Z-axis, which distributes to the increase in exposure dose according to the rise of scattered ray. Also MDCT brings out the increase of scattered ray about 4times more than SDCT. To evaluate scattered ray according to the change of beam thickness on MDCT, we measured scattered ray of MDCT's Z-axis beam thickness by using one 16-slice CTs and two 64-slice CTs. We used the ionization chamber 60ml 2026C as the equipment of measurement. In our results, we found out that the change of scattered ray according to the beam thickness in the same kVp has increase of scattered ray. Secondly we found out the increase of scattered ray according to the increase of kVp. Lastly we found out the decrease of scattered ray according to the increase of the distance from the ionization chamber.

• Journal of the Korean Society of Radiology
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• v.10 no.5
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• pp.291-298
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• 2016

Recently, the interest in the orthodontic treatment for children is increased by a rise in national income level. The number of cephalometric radiography that could diagnose a malocclusion and malposition between teeth and jawbone increased. It required attention to radiation exposure, because the subject of dental examination is children which are more sensitive to radiation and the head and neck, the object of that include radiation sensitive organ such as the thyroid, bone marrow, eyes, salivary gland, and so on. In this study, we measured two-dimensional dose distribution in cephalometric radiography system (VATEC Pax-400C) using Agfa CP-G Plus film and MagicMax Dosimeter, and calculated radiation organ dose of head and neck through MCNPX simulation. And then we designed a radiation protective device to decrease radiation dose. The dose distribution of the cephalometric radiography system irradiated the head and neck overall as well as the oral and maxillofacial parts. The radiation organ dose calculated that thyroid, oesophagus and eyes are irradiated high, and the radiation organ dose decreased about 70 ~ 80% by the application of the radiation protective device. The results of this study will be used construction of database for dental radiation exposure and research of reducing radiation dose.

• The Journal of Korean Society for Radiation Therapy
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• v.20 no.2
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• pp.103-107
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• 2008

Purpose: This paper describes a electron field presence of magnetic field, intensity and shape surface dose variation to clinical application possibility. Materials and Methods: The using 6 MeV electron and $10{\times}10\;cm^2$ field size, 9 hole to shielding block make the by measure the film, when the magnetic field position inside and outside of the X-Omat film and parallel plate ionization chamber using the surface dose measured. Results: Present of 4 cm to the side at angle about 3 degree from beam center, use of ring type magnetic is 0.9% increase the surface dose, lens block located in the magnetic field the surface dose 1.58% increase, half magnetic field's position on the side of them at the field center of the 3.6% increase of the surface dose. Conclusion: Surface dose variation is with magnetic field about the mean electron beam of progress direction change, orbit region patient's is inconvenient without surface dose increase percentage case goodness will be used as a useful way.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.165-171
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• 2002

Purpose : In order to perform craniospinal irradiation (CSI) in the supine position on patients who are unable to lie in the prone position, a new simulation technique using a CT simulator was developed and its availability was evaluated. Materials and Method : A CT simulator and a 3-D conformal treatment planning system were used to develop CSI in the supine position. The head and neck were immobilized with a thermoplastic mask in the supine position and the entire body was immobilized with a Vac-Loc. A volumetrie image was then obtained using the CT simulator. In order to improve the reproducibility of the patients' setup, datum lines and points were marked on the head and the body. Virtual fluoroscopy was peformed with the removal of visual obstacles such as the treatment table or the immobilization devices. After the virtual simulation, the treatment isocenters of each field were marked on the body and the immobilization devices at the conventional simulation room. Each treatment field was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR)/digitally composite radiography (DCR) images from the virtual simulation. The port verification films from the first treatment were also compared with the DRR/DCR images for a geometrical verification. Results : CSI in the supine position was successfully peformed in 9 patients. It required less than 20 minutes to construct the immobilization device and to obtain the whole body volumetric images. This made it possible to not only reduce the patients' inconvenience, but also to eliminate the position change variables during the long conventional simulation process. In addition, by obtaining the CT volumetric image, critical organs, such as the eyeballs and spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. The differences between the DRRs and the portal films were less than 3 mm in the vertebral contour. Conclusion : CSI in the supine position is feasible in patients who cannot lie on prone position, such as pediatric patienta under the age of 4 years, patients with a poor general condition, or patients with a tracheostomy.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.186-192
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• 2002

Purpose : Measurement of transmission dose is useful for in vivo dosimetry. In this study, previous algorithm for estimation of transmission dose was modified for use in cases with tissue deficit. Materials and Methods : The beam data was measured with flat solid phantom in various conditions of tissue deficit. New algorithm for correction of transmission dose for tissue deficit was developed by physical reasoning. The algorithm was tested in experimental settings with irregular contours mimicking breast cancer patients using multiple sheets of solid phantoms. Results : The correction algorithm for tissue deficit could accurately reflect the effect of tissue deficit with errors within ${\pm}1.0\%$ in most situations and within ${\pm}3.0\%$ in experimental settings with irregular contours mimicking breast cancer treatment set-up. Conclusion : Developed algorithm could accurately reflect the effect of tissue deficit and irregularly shaped body contour on transmission dosimetry.

• Progress in Medical Physics
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• v.14 no.2
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• pp.90-98
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• 2003

Purpose : A new virtual simulation technique for craniospinal irradiation (CSI) that uses a CT-simulator was developed to improve the accuracy of field and shielding placement as well as patient positioning. Materials and Methods : A CT simulator (CT-SIM) and a 3-D conformal radiation treatment planning system (3D-CRT) were used to develop CSI. The head and neck were immobilized with a thermoplastic mask while the rest of the body was immobilized with a Vac-Loc. A volumetric image was then obtained with the CT simulator. In order to improve the reproducibility of the setup, datum lines and points were marked on the head and body. Virtual fluoroscopy was performed with the removal of visual obstacles, such as the treatment table or immobilization devices. After virtual simulation, the treatment isocenters of each field were marked on the body and on the immobilization devices at the conventional simulation room. Each treatment fields was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR) and digitally composited radiography (DCR) images from virtual simulation. Port verification films from the first treatment were also compared with the DRR/DCR images for geometric verification. Results : We successfully performed virtual simulations on 11 CSI patients by CT-SIM. It took less than 20 minutes to affix the immobilization devices and to obtain the volumetric images of the entire body. In the absence of the patient, virtual simulation of all fields took 20 min. The DRRs were in agreement with simulation films to within 5 mm. This not only reducee inconveniences to the patients, but also eliminated position-shift variables attendant during the long conventional simulation process. In addition, by obtaining CT volumetric image, critical organs, such as the eyes and the spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. Differences between the DRRs and the portal films were less than 3 m in the vertebral contour. Conclusion : Our analysis showed that CT simulation of craniospinal fields was accurate. In addition, CT simulation reduced the duration of the patient's immobility. During the planning process. This technique can improve accuracy in field placement and shielding by using three-dimensional CT-aided localization of critical and target structures. Overall, it has improved staff efficiency and resource utilization by standard protocol for craniospinal irradiation.