• Radiation Oncology Journal
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• v.10 no.1
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• pp.85-93
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• 1992

We have studied the dosimetric properties of electron beam using Lyon intraoperative device for intraoperative radiation therapy. The dosimetry data had compiled in such a way that a quick and correct decision regarding the cone shape, energy, and accurate calculations could be made. Using 3 dimensional water phantom, we have got the following data: cone output ratios, surface dose, $d_{max}$, $d_{90}$, flatness, symmetry, beam profiles, isodose curve, and SSD correction factors. The cone output ratios were measured with straight and bevelled cone, respectively. As the cone size and the energy were reduced, the cone output ratios decreased rapidly. With the flattening filter, the surface dose increased by electron beam to $85.3\%$, $89.2\%$, and $93.4\%$, for 6 MeV, 9 MeV, and 12 MeV, respectively. It is important to increase the surface dose to $90\%$ or more. Inspite of diminishing dose rate and beam penetration, this flattening filter increases the treatment volume significantly. With the combination of the three levels collimation and the flattening filter, we achieved good homogeneity of the beam and better flatness and the diameter of the 90$\%$ isodose curve was increased. It is important to increase the area that is included in the $90\%$ isodose level. The value of measured and calculated SSD correction factors did not agree over the clinically important range from 100 cm to 110 cm.

• Journal of the Korean Society of Radiology
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• v.13 no.5
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• pp.791-799
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• 2019

We evaluated the physical properties that occur to dose enhancement and changes from secondary particle production resulting from the interaction between enhancement material. Geant4 was used to perform a Monte Carlo simulation, and the medical internal radiation dose (MIRD) head phantom were employed. X-rays of 4, 6, 10, 15, 18, and 25 MV were used. Aurum (Au) and gadolinium (Gd) were applied within the tumor volume at 10, 20, and 30 mg/g, and an experiment using soft tissue exclusively was concomitantly performed for comparison. Also, particle fluence and initial kinetic energy of secondary particle of interaction were measured to calculate equivalent doses using the radiation weight factor. The properties of physical interaction by the radiation enhancement material showed the great increased in photoelectric effect as compared to the compton scattering and pair production, occurred with the highest, in aurum and gadolinium it is shown in common. The photonuclear effect frequency increased as the energy increased, thereby increasing secondary particle production, including alpha particles, protons, and neutrons. During dose enhancement using aurum, a maximum 424.25-fold increase in the equivalent dose due to neutrons was observed. This study was Monte Carlo simulation corresponds to the physical process of energy transmission in dose enhancement. Its results may be used as a basis for future in vivo and in vitro experiments aiming to improve effects of dose enhancement.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.262-266
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• 2013

A new concept of periapical radiography, intra oral x-ray tube and detector system is introduced. It is new system that a miniature x-ray tube is inserted into mouse and it acquired digital image using external detector. In this study, we have investigated temperature and dose distribution of insertional x-ray tube for periapical radiography. To analyze temperature characteristic of x-ray tube, we attached the thermocouple to surface of x-ray tube and we measured the temperature according to distance. Also, we measured the dose distribution of a miniature x-ray tube according to distance. As a result, temperature was constant to $27^{\circ}C$ over 2mm without cooling system, dose distribution of x-ray tube was 3.14 and 1.84mGy in 3 and 5cm, respectively. Therefore, the proposed x-ray system works in lower dose than conventional dental x-ray system. Thus, it is considered that new concept of system will have a significant effect on medical imaging technology.

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.230-231
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• 2011

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.56-57
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• 2011

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.290-291
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• 2009

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.264-265
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• 2009

• Journal of Sensor Science and Technology
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• v.9 no.3
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• pp.213-223
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• 2000

It is necessary that radiation dose would be detect exactly generated from facility related to nuclear, space, radiotherapy center, etc. This paper is to use of the radiation-induced threshold voltage change as an accumulated radiation dose monitoring sensor. Commercial P Channel Power MOSFET(metal oxide field effect transistor) were tested in a Co-60 gamma irradiation facility to see their capabilities as a radiation dosimeter. We found that the transistors showed good linearity in their threshold voltage shift characteristics with radiation dose. The results demonstrate the potential use of commercial P Channel Power MOSFET as inexpensive radiation sensors.

• Progress in Medical Physics
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• v.5 no.2
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• pp.21-26
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• 1994

By measuring with TLD, absorbed dose of rectum will be determined more accurately than calculated value. MgB$_4$O$\sub$7/(Mn) TLD phosphor was prepared and its characteristic was studied. To measure the absorbed dose of rectum with TLD, 33 patients who had intracavitary treatment with $\^$60/Co from April 1994 to September 1994 at Kosin Medical center. There were 10-59% differecne in most cases between the calculation and the measurement for the absorbed dose of rectum. The difference was less the case with tandem and ovoid than the case with only ovoid.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.497-502
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• 2003

Landfill is an widely applied alternative for clearance of non-contaminated waste or slightly contaminated waste generated from nuclear facilities. In this study, exposure dose is estimated for a worker and a resident at the landfill area in Young-gwang nuclear power plant. Based on evaluated dose, clearance concentrations of each radionuclide are determinated for dose criteria of 10 $\muSv/y$. The results of age-dependent dose are 1.02 $\muSv$ per year for resident and 0.471 $\muSv$ per year for worker. Clearance concentrations for each radionuclide are evaluated from $1.33{\times}10_{-1}$ Bq per gram to $2.85{\times}10^2$ Bq per gram.