• Journal of the Korean Society of Radiology
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• v.10 no.6
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• pp.375-379
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• 2016

A rat is the most common experimental animal used for the realization of the radiation injury model. The certain thickness of rat skin was prepared by peeling off a rat skin. Radiation level was measured by using this rat skin. Also, The schematic of the formula was made that can predict the radiation absorbed dose (RAD) as a function of the thickness of the rat skin. Consequently, we will provide the RAD information in the realization of in-vitro experimental model regarding the rat's skin thickness by applying the formulas. Moreover, the results from this study can be effectively used for the in-vitro experiment of the rat subcutaneous tissue which was exposed to radiation.

• Progress in Medical Physics
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• v.9 no.3
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• pp.155-162
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• 1998

Ho-l66 was produced by neutron reaction in a reactor at the Korea Atomic Energy Institute (Taejon, Korea). Ho-l66 emits a high energy beta particles with a maximum energy of 1.85 MeV and small proportion of gamma rays (80 keV). Therefore, the radiation absorbed dose estimation could be based on the in-vivo quantification of the activity in tumors from the gamma camera images. Approximately 1 mCi of Ho-l66 in solution was mixed into the flood phantom and planar scintigraphic images were acquired with and without patient interposed between the phantom and scintillation camera. Transmission factor over an area of interest was calculated from the ratio of counts in selected regions of the two images described above. A dual-head gamma camera(Multispect2, Siemens, Hoffman Estates, IL, USA) equipped with medium energy collimators was utilized for imaging(80 keV${\pm}$10%). Fifty-nine year old female patient with hepatoma was enrolled into the therapeutic protocol after the informed consent obtained. Thirty millicuries(110MBq) of Ho-166-CHICO was injected into the right hepatic arterial branch supplying hepatoma. When the injection was completed, anterior and posterior scintigraphic views of the chest and pelvic regions were obtained for 3 successive days. Regions of interest (ROIs) were drawn over the organs in both the anterior and posterior views. The activity in those ROIs was estimated from geometric mean, calibration factor and transmission factors. Absorbed dose was calculated using the Marinelli formula and Medical Internal Radiation Dose (MIRD) schema. Tumor dose of the patient treated with 1110 MBq(30 mCi) Ho-l66 was calculated to be 179.7 Gy. Dose distribution to normal liver, spleen, lung and bone was 9.1, 10.3, 3.9, 5.0 % of the tumor dose respectively. In conclusion, tumor dose and absorbed dose to surrounding structures were calculated by daily external imaging after the Ho-l66 therapy for hepatoma. In order to limit the thresholding dose to each surrounding organ, absorbed dose calculation provides useful information.

• Journal of the Korean Society of Radiology
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• v.5 no.6
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• pp.383-389
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• 2011

This study offered a new method to calculate absorbed dose of actual patients through Monte Carlo Simulation by using the linkage of Geant4 and DICOM, and, the experimental value of absorbed dose at the center and Geant 4 simulation result according to the depth of PMMA mock phantom were compared by using MOSEF in order to verify Geant4 calculation code. In the area where there was no air space between the irregular gap due to incomplete compression of PMMA slab, the differences were $0.46{\pm}4.69$ percent and $-0.75{\pm}5.19$percent in $15{\times}15cm^2$ and $20{\times}20cm^2$ respectively. Excluding the error due to incomplete compression of PMMA mock phantom, the calculation values of the Monte Carlo simulation by linkage of Geant4 and DICOM was the same.

• Progress in Medical Physics
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• v.13 no.2
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• pp.62-68
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• 2002

A muiltileaf collimator (MLC) is used as a replacement for conventional blocks. The MLC, however may not be appropriate for a fine field shaping. For the fine field shaping, conventional block can be added under the MLC. But it may significantly affect on the dosimetric characteristics such as surface dose of skin, buildup region and percent depth doses. We performed the study to evaluate the surface dose and the maximum depth dose using MLC conjunction with conventional blocks for various field sizes and energies. We confirmed the surface dose was increased by using the additional conventional block under the MLC ranging from 10 to 35.6％ according to various field sizes and radiation beam energies. The surface dose was effectively reduced by application of 2 or 3 m thickness of lead plate as electron filter.

• The Journal of the Korea Contents Association
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• v.17 no.9
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• pp.292-299
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• 2017

Radiation protection aims to prevent a deterministic effect and minimize a stochastic effect. Overestimating a deterministic effect and a stochastic effect can result in an inaccurate assessment of the risks that will occur in the future, and thus accurate evaluation of the absorbed dose of these fundamental amounts is especially important. This study was intended to measure Kerma using PCXMC 2.0 based on Monte Carlo simulations and to assess the exact absorbed dose by comparing doses produced using multipurpose dosimeter and glass dosimeter. It has been decided to conduct experiments for skull, abdomen and pelvis, and Kerma measured PCXMC 2.0 based on Monte Carlo simulations. The absorbed dose was measured using muli purpose dosimeter and glass dosimeter. The results for the experiments conducted in skull, abdomen, pelvis show that the difference in dose appears great in the order of PCXMC 2.0, muli purpose dosimeter, and the glass dosimeter, and muli purpose dosimeter showed a value closer to that of Kerma. As a result, it has been found that the glass dosimeter was the most advantageous in measuring the actual absorbed dose.

• Radiation Oncology Journal
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• v.17 no.3
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• pp.256-260
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• 1999

Purpose : An investigation has been carried out on the factors which affect the response reading of thermoluminescent dosimeters (TLD-100) loaded with thin material in high energy Photon. The aim of the study was to assess the energy response of TLD-100 to the therapeutic ranges of photon beam. Materials and Methods : In this technique, TLD-100 (abbreviated as TLD) chips and three different thin material (Tin, Gold, and Tissue equivalent plastic plate) which mounted on the TLD chip were used in the clinical photon beam. The thickness of each metal plates was 0.1 mm and TE plastic plate was 1 mm thick. These compared with the photon energy dependence of the sensitivities of TLD (normal chip), TLD loaded with Tin or Gold plate, for the photon energy range 6 MV to 15 MV, which was of interest in radiotherapy. Results : The enhancement of surface dose in the TLD with metal plate was clearly detected. The TLD chips with a Gold plate was found to larger response by a factor of 1.83 in 10 MV photon beam with respect to normal chip. The sensitivity of TLD loaded with Tin was less than that for normal TLD and TLD loaded with Gold. The relative sensitivity of TLD loaded with metal has little energy dependence. Conclusion : The good stability and linearity with respect to monitor units of TLD loaded with metal were demonstrated by relative measurements in high energy Photon ($6\~15$ MV) beams. The TLD laminated with metals embedded system in solid water phantom is a suitable detector for relative dose measurements in a small beam size and surface dose.

• Progress in Medical Physics
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• v.24 no.3
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• pp.140-144
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• 2013

In this research, the glass dosimeter was calibrated to measure the standard absorbed dose of the Cs-137 irradiator and absorbed dose in a biological sample. Absorbed dose in water for Cs-137 gamma ray was determined by the IAEA TRS-277 protocol. The PTW-TM30013 ion chamber and the PTW-TM41023 water phantom were utilized for measuring absorbed dose and the value was compared with the reading from DoseAce GD-302M glass dosimeter from Asahi Techno Glass Corporation for its calibration. The uncertainty of measurement ($1{\sigma}$) of the calibrated glass dosimeter was 2.7% and this result would be applied to improve the accuracy in measurement of absorbed dose in a biological sample.

• Progress in Medical Physics
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• v.13 no.2
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• pp.98-103
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• 2002

The purpose of this study was to evaluate the absorbed dose to the coronary artery segment from various sized balloon angio catheters. The liquid form of Ho-166 was produced at the KAERI by (n, ${\gamma}$ ) reaction. We used GafChromic film for the estimation of the absorbed dose by beta particles. The exposed films were read using a videodensitometer. Several film exposures were made with varying irradiation times and activities. A modified micrometer was used for the measurement of the absorbed dose distribution near the balloon surface. Four balloons of coronary catheters evaluated were 30 m long and 2.5, 3.0, 3.5 and 4.0 mm in diameter. All doses are plotted in units of Gy/min/GBq/ml as a function of radial distance in mm from the surface of balloon. The absorbed dose rate was 0.86, 1.01, 1.11 and 1.24 Gy/min/GBq/ml at a balloon surface for various balloon diameter 2.5, 3.0, 3.5 and 4.0 mm respectively. Using a vacuum pump, the air in the balloon was evacuated prior to instillation of the Ho-166 source. By removing air bubbles in the balloon, the absorbed dose distribution was more uniform.

• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.467-474
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• 2014

The relative dose calculated by MCNPX and the relative dose measured by ionization chamber and solid phantoms evaluated the accuracy comparing with Monte Carlo simulation. In order to apply Monte Carlo simulation the intraluminal brachytherapy of extrahepatic bile duct cancer, 192Ir sealed radioactive source replicate, Bile duct and surrounding organs were made using KMIRD phantom based on a South Korea standard man. To check the absorbed dose of normal organs around bile duct, we set the specific effective energy and initial radioactivity to 1 Ci using MCNPX. Evaluation of the accuracy of the Monte Carlo simulation, the difference of the relative dose is the most 1.96% that satisfy the criteria that is the relative error less than 2% suggested by MCNPX code. In addition, The specific effective energy and absorbed dose of normal organs that were relatively adjacent to bile duct such as right side of kidney, liver, pancreas, transverse colon, spinal cord, stomach and small intestine were relatively high. on the contrary, the organs that were relatively distant to bile duct such as left side of kidney, spleen, ascending colon, descending colon and sigmoid colon were relatively low.

• Journal of Radiation Protection and Research
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• v.28 no.4
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• pp.321-325
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• 2003

The effects of AMAD, absorption type, and intake pattern were compared and analysed for the internal dose evaluation of workers who chronically inhale uranium. The committed effective doses$(E_{50})$ based on AMAD, absorption type, and intake pattern were evaluated using 3 monthly lung predicted monitoring data due to a chronic intake of uranium for 5 years. The relative error ranges of $E_{50}$ evaluated with each AMAD$(0.1{\sim}10{\mu}m)\;to\;E_{50}$ evaluated with $5{\mu}m$ AMAD were $-37.0{\sim}49.8%$, and the relative error ranges of En evaluated with Type M to $E_{50}$ evaluated with Type S were $15.9{\sim}56.6%$, and the relative error ranges of $E_{50}$ evaluated with an acute intake to $E_{50}$ evaluated with a chronic intake were $0.55{\sim}4.52%$. Thus AMAD and the absorption type affected the results of $E_{50}$, but the intake pattern didn't really affect the results of $E_{50}$.